HVAC/R Certification Exam — Questions and Answers

Question 1: When disposing of an appliance containing CFC, HCFC, or HFC refrigerant, EPA Section 608 regulations require that:

The refrigerant must be recovered by an EPA-certified technician. (Correct answer)
The appliance owner must transport it to a certified disposal facility.
Systems with less than 5 pounds of refrigerant can be vented.
The refrigerant must be reclaimed before disposal.

Correct answer: The refrigerant must be recovered by an EPA-certified technician.

Under EPA Section 608 of the Clean Air Act, it is mandatory for all refrigerant to be recovered from an appliance before its final disposal. This task must be performed by a technician who holds an EPA 608 certification.

Question 2: What does a high-side pressure reading significantly above normal indicate during AC diagnosis?

Compressor clutch slipping
Restricted or failing condenser (Correct answer)
Low refrigerant charge
Faulty expansion valve stuck open

Correct answer: Restricted or failing condenser

Abnormally high discharge-side pressure typically points to poor condenser airflow, a dirty condenser coil, or a failing condenser fan that prevents heat rejection.

Question 3: A technician finds a burned 5-amp fuse on the control board. After replacing it, the fuse blows immediately. What is the correct next step?

Check all 24V control wiring for a short to ground (Correct answer)
Install a higher-rated fuse
Replace the control board
Measure high-voltage supply to the board

Correct answer: Check all 24V control wiring for a short to ground

An immediately blown fuse indicates a short in the low-voltage circuit; the wiring must be traced to find the short before replacing the fuse again.

Question 4: On a heat pump system, the reversing valve solenoid is energized in cooling mode. If the solenoid coil reads infinite resistance, what will happen?

The system will operate in heating mode only (Correct answer)
The thermostat will lose its display
The compressor will short-cycle
The outdoor fan will not run

Correct answer: The system will operate in heating mode only

An open reversing valve solenoid coil means the valve cannot be electrically shifted, leaving it in its de-energized (heating) position.

Question 5: When installing a ductless mini-split, the wall sleeve (line set hole) should be drilled at a slight downward angle toward the outside to:

Allow condensate from the wall sleeve area to drain outdoors (Correct answer)
Allow easier electrical wire routing
Improve refrigerant flow velocity
Reduce vibration transmission into the wall

Correct answer: Allow condensate from the wall sleeve area to drain outdoors

A slight downward pitch toward the exterior ensures any water that enters the wall sleeve hole drains outward rather than into the structure.

Question 6: A technician responds to a no-cool call. The indoor blower is running, and the thermostat is calling for cooling, but the outdoor unit is silent except for a faint humming sound. The condenser fan is not spinning. Which of the following is the MOST likely cause of this specific symptom?

A stuck reversing valve
A faulty thermostat
A failed dual-run capacitor (Correct answer)
A tripped circuit breaker for the condensing unit

Correct answer: A failed dual-run capacitor

A dual-run capacitor serves both the compressor and the condenser fan motor. If it fails, neither component will have the necessary stored energy and phase shift to start, often resulting in a humming sound as the motors attempt to turn but cannot. A tripped breaker would result in no power and no humming. A faulty thermostat would likely not send the 24V signal to the outdoor unit at all. A stuck reversing valve would cause performance issues but would not prevent the compressor and fan from starting.

Question 7: A condensing unit is located in a pit below grade level. What is the primary concern with this installation?

The electrical disconnect is inaccessible
Refrigerant lines will be too short
Hot air discharge will recirculate into the unit, reducing efficiency and capacity (Correct answer)
The unit cannot be properly leveled

Correct answer: Hot air discharge will recirculate into the unit, reducing efficiency and capacity

A condensing unit in a below-grade pit tends to trap its own hot discharge air, causing high head pressure, reduced efficiency, and potential high-pressure lockout.

Question 8: When insulating suction line tubing on an AC installation, the insulation must be:

Applied only at the outdoor unit connection
Continuous with no gaps, joints sealed, and of adequate wall thickness (Correct answer)
Installed over the liquid line only
Limited to areas exposed to direct sunlight only

Correct answer: Continuous with no gaps, joints sealed, and of adequate wall thickness

Suction line insulation must be continuous and fully sealed to prevent condensation, heat gain, and capacity loss throughout the entire lineset run.

Question 9: What symptom would a technician observe if the reversing valve on a heat pump is stuck in the heating position?

Compressor overheats only in heating mode
No heating or cooling available
No cooling in summer, heating works normally (Correct answer)
Cooling and heating work but efficiency is low

Correct answer: No cooling in summer, heating works normally

If the reversing valve is stuck in heating mode, the system will heat in both summer and winter, providing no cooling when switched to cooling mode.

Question 10: The condensate drain line for a horizontal air handler installed in an attic should include:

A check valve to prevent backflow
A UV light to sterilize condensate
Only the primary drain — secondary systems are optional
A secondary drain pan with a separate overflow drain or safety switch (Correct answer)

Correct answer: A secondary drain pan with a separate overflow drain or safety switch

Attic-installed air handlers require a secondary condensate pan with drain or float switch to prevent ceiling water damage if the primary drain clogs.

Question 11: A contactor's coil is rated at 24V but the unit reads only 18V at the coil terminals during a call for cooling. What is the most likely cause?

Overcharged refrigerant system
Incorrect thermostat setting
Shorted contactor contacts
Low voltage from the transformer secondary (Correct answer)

Correct answer: Low voltage from the transformer secondary

Insufficient transformer output or excessive voltage drop in the 24V control circuit causes low coil voltage, preventing the contactor from pulling in fully.

Question 12: A thermostatic expansion valve is a part of an air conditioning system. The compressor's suction line feels chilly to the touch. this signals:

A stuck open thermostatic expansion valve
A stuck closed thermostatic expansion valve
Normal condition (Correct answer)
A low refrigerate charge

Correct answer: Normal condition

In a properly functioning air conditioning system, the compressor's suction line (the larger, insulated line returning to the compressor) should feel cool or chilly to the touch. This sensation indicates that the refrigerant is returning to the compressor in a low-pressure, cool gaseous state after effectively absorbing heat from the indoor air. Therefore, a chilly suction line is a normal and expected condition.

Question 13: A technician measures capacitor capacitance and finds it reads 38 MFD on a capacitor rated 45 MFD ±6%. Is the capacitor within tolerance?

No, it is below the allowable tolerance range (Correct answer)
Yes, it is within the ±6% tolerance
No, only readings above 42 MFD are acceptable
Yes, any reading above 35 MFD is acceptable

Correct answer: No, it is below the allowable tolerance range

±6% of 45 MFD gives an acceptable range of 42.3–47.7 MFD; 38 MFD is below this range and the capacitor must be replaced.

Question 14: A condenser fan motor runs but the compressor does not start and hums loudly. Capacitance testing shows the HERM section of the dual-run capacitor is reading 12 MFD instead of 40 MFD. What is the correct action?

Replace the compressor contactor
Replace the dual-run capacitor with one matching the original MFD and voltage ratings (Correct answer)
Replace only the FAN section of the capacitor
Add a second capacitor in parallel to make up the difference

Correct answer: Replace the dual-run capacitor with one matching the original MFD and voltage ratings

A degraded capacitor must be replaced with one of matching MFD and equal or higher voltage rating; adding capacitors in parallel is not an approved field repair.

Question 15: A residential split system is being installed in a garage. What special consideration applies to the condensing unit's electrical disconnect?

A fused disconnect must be within sight of and readily accessible from the unit (Correct answer)
The disconnect must be rated for outdoor use only if the garage is unheated
No disconnect is needed if the breaker is within 50 feet
A GFCI outlet can substitute for a disconnect

Correct answer: A fused disconnect must be within sight of and readily accessible from the unit

NEC 440.14 requires a disconnect within sight of and readily accessible from the condensing unit to allow safe service lockout.

Question 16: To accurately evaluate total system airflow and diagnose potential restrictions in ductwork, which of the following measurements is most essential?

Velocity pressure in the return duct
Total external static pressure (Correct answer)
Temperature drop across the evaporator coil
Amperage draw of the indoor blower motor

Correct answer: Total external static pressure

Total external static pressure is the measurement of resistance (pressure) the blower must work against in both the supply and return ducts. A reading higher than the manufacturer's specification indicates a restriction to airflow, such as a dirty filter, clogged coil, or undersized ducts.

Question 17: What does a high delta-T (temperature difference) across the evaporator coil typically indicate?

Dirty condenser coil
Good system performance with proper heat absorption (Correct answer)
Low refrigerant charge
Overcharged refrigerant

Correct answer: Good system performance with proper heat absorption

A temperature difference of 16–22°F across the evaporator coil typically indicates the system is properly absorbing heat and operating efficiently.

Question 18: What is ACCA Manual J used for in the HVAC industry?

Selecting refrigerant recovery equipment
Sizing commercial duct systems
Performing residential load calculations (Correct answer)
Calculating EPA refrigerant allowances

Correct answer: Performing residential load calculations

ACCA Manual J is the industry-standard method for calculating residential heating and cooling loads to properly size HVAC equipment.

Question 19: What happens in a condenser in a cooling and refrigeration system?

The refrigerant releases the latent heat. (Correct answer)
Latent heat is increased
Latent heat is pressurized.
The refrigerant absorbs the latent heat.

Correct answer: The refrigerant releases the latent heat.

In a condenser, the high-pressure, high-temperature gaseous refrigerant releases its latent heat to the cooler ambient air, typically aided by a fan. As it releases this heat, the refrigerant changes phase from a gas back into a liquid. This process is essential for dissipating the heat absorbed from the cabin and completing the refrigeration cycle.

Question 20: When using an electronic leak detector on an air conditioning system, the probe should be moved:

Only along the top of refrigerant lines
Rapidly across the entire unit
Directly over the Schrader valves only
Slowly along the bottom of fittings and connections (Correct answer)

Correct answer: Slowly along the bottom of fittings and connections

Refrigerant vapor is heavier than air and settles downward, so moving the probe slowly along the bottom of fittings ensures detection of leaking vapors.

Question 21: A technician is performing an evacuation on a newly installed system. After isolating the vacuum pump, the technician observes the vacuum level rises from 400 microns and stabilizes at 1,500 microns. What is the most likely cause of this behavior?

A faulty micron gauge giving an incorrect reading
Moisture is still present and boiling off within the system (Correct answer)
A large leak in the flare connections
The vacuum pump oil needs to be changed

Correct answer: Moisture is still present and boiling off within the system

When a deep vacuum is pulled, the boiling point of water drops significantly. A vacuum level that rises and then holds steady indicates that trapped liquid water is boiling into vapor, which increases the system pressure. Once all the liquid has boiled off, the pressure stabilizes. A leak would typically cause the pressure to continue rising towards atmospheric pressure.

Question 22: What is the purpose of an access port Schrader valve core removal tool during service?

To test for valve leaks
To replace a damaged Schrader valve while the system is pressurized
To add dye to the system
To allow full-flow refrigerant access without restricting flow through the valve core (Correct answer)

Correct answer: To allow full-flow refrigerant access without restricting flow through the valve core

Removing the Schrader core allows unrestricted flow for faster recovery and more accurate pressure readings, as the core itself creates flow restriction.

Question 23: When an AC outdoor unit is installed on a rooftop, the mounting platform must:

Be constructed of wood for flexibility
Be secured with standard wood screws only
Be structurally rated for the unit weight and allow for vibration isolation (Correct answer)
Be elevated exactly 12 inches above the roof surface

Correct answer: Be structurally rated for the unit weight and allow for vibration isolation

Rooftop installations require structurally adequate, properly rated supports with vibration isolation pads to protect both the unit and the roof structure.

Question 24: Which type of motor protection device senses both motor current and winding temperature to prevent compressor burnout?

Current transformer
Phase monitor relay
Internal motor protector (IMP) (Correct answer)
Potential relay

Correct answer: Internal motor protector (IMP)

An internal motor protector monitors both winding temperature and current, opening the circuit if either exceeds safe limits to protect the compressor.

Question 25: How does uncontrolled air infiltration affect a building's cooling load?

It only affects the heating load, not the cooling load
It adds both sensible and latent load by introducing unconditioned outdoor air (Correct answer)
It has no measurable effect on the cooling load
It reduces the load by diluting indoor heat sources

Correct answer: It adds both sensible and latent load by introducing unconditioned outdoor air

Infiltration introduces hot, humid outdoor air through gaps and cracks in the building envelope, adding both sensible heat (temperature) and latent load (moisture) that the AC system must handle.

Question 26: Which measurement indicates proper lubrication is needed on older belt-drive blower motors?

Low static pressure in the duct system
Motor running hot above its rated temperature or unusual squealing noise (Correct answer)
Low suction pressure at the service valve
High delta-T across the evaporator

Correct answer: Motor running hot above its rated temperature or unusual squealing noise

Excessive heat or squealing from a belt-drive motor bearing signals inadequate lubrication and potential bearing failure.

Question 27: A technician is troubleshooting an air handler that blows warm air in cooling mode. The compressor and condenser fan are running. What electrical component failure could cause this symptom?

Open circuit in the reversing valve solenoid (heat pump) (Correct answer)
Shorted contactor holding coil
Open circuit in the indoor blower capacitor
Failed thermostat R-terminal fuse

Correct answer: Open circuit in the reversing valve solenoid (heat pump)

On a heat pump, an open reversing valve solenoid coil prevents the valve from switching to cooling mode, causing the system to deliver warm air.

Question 28: A split-system air conditioner has a normal suction pressure but an abnormally high discharge pressure. The MOST likely cause is:

Dirty or blocked condenser coil (Correct answer)
Low refrigerant charge
Restricted filter drier
Faulty TXV

Correct answer: Dirty or blocked condenser coil

A dirty condenser coil reduces heat rejection, causing refrigerant to remain at a higher temperature and pressure on the high side.

Question 29: When testing a dual-run capacitor with a multimeter, a technician should measure the microfarad (µF) reading between which terminals to check the capacitance for the compressor motor?

Between the 'C' (Common) and 'FAN' terminals.
Across any two of the three terminals.
Across the 'HERM' and 'FAN' terminals.
Between the 'C' (Common) and 'HERM' (Hermetic) terminals. (Correct answer)

Correct answer: Between the 'C' (Common) and 'HERM' (Hermetic) terminals.

A dual-run capacitor has three terminals: Common (C), Fan, and Hermetic (HERM) for the compressor. To test the capacitance for the compressor winding, the multimeter probes must be placed on the 'C' and 'HERM' terminals. The reading should be compared to the rating stamped on the capacitor.

Question 30: A car's AC blows cold for 10 minutes then gradually turns warm. What is the most likely cause?

Faulty compressor clutch
Clogged cabin air filter
Weak blower motor
Icing of the evaporator due to low refrigerant (Correct answer)

Correct answer: Icing of the evaporator due to low refrigerant

Low refrigerant causes the evaporator coil to drop below freezing, forming ice that blocks airflow; once the ice melts, cooling briefly returns before icing again.

Question 31: A technician uses a megohmmeter to test a compressor motor winding to ground. A reading of 2 megohms is obtained. What does this indicate?

The winding insulation is acceptable
The winding has failed completely
Moisture or degraded insulation is present (Correct answer)
The test is inconclusive without a capacitor reading

Correct answer: Moisture or degraded insulation is present

A compressor winding-to-ground reading below 1,000 megohms suggests compromised insulation, likely from moisture ingress or winding breakdown.

Question 32: How often should air conditioning system air filters typically be inspected or replaced in a residential application?

Once every 2 years
Only when the system stops cooling
Every 1–3 months depending on usage and filter type (Correct answer)
At the time of installation only

Correct answer: Every 1–3 months depending on usage and filter type

Residential AC air filters should be inspected monthly and replaced every 1–3 months to maintain airflow and system efficiency.

Question 33: In load calculations, the U-value of a building assembly describes which property?

The thermal resistance of the insulation layer
The overall heat transfer coefficient of the assembly (Correct answer)
The solar absorptance of the exterior surface
The air leakage rate through the assembly

Correct answer: The overall heat transfer coefficient of the assembly

U-value is the overall heat transfer coefficient, expressing how much heat flows through an assembly per square foot per degree of temperature difference; it is the mathematical inverse of R-value.

Question 34: When using a system-dependent (passive) recovery process on a small appliance with an operating compressor, the technician should connect their recovery device to:

Both the high and low sides.
The high side only. (Correct answer)
The liquid line service port.
The low side only.

Correct answer: The high side only.

When the compressor is operational, it pushes the refrigerant into the high-pressure side of the system (condenser). Connecting to the high side takes advantage of the compressor's work to quickly and efficiently recover the refrigerant.

Question 35: When using an electronic leak detector on an HFC system, which type of sensor is most appropriate?

Ultrasonic detector
Heated diode (heated pentode)
Halide torch
Infrared sensor (Correct answer)

Correct answer: Infrared sensor

Infrared sensors are highly accurate for HFC refrigerants and are not destroyed by exposure to refrigerant the way heated diode sensors can be.

Question 36: What is the purpose of checking and tightening electrical connections during preventive maintenance?

To reduce refrigerant charge requirements
To increase system airflow
To lower the superheat setting
To prevent resistance heating, arcing, and component failure (Correct answer)

Correct answer: To prevent resistance heating, arcing, and component failure

Loose electrical connections create resistance, generate heat, cause arcing, and can lead to component or control board failures.

Question 37: The process of adding heat to the refrigerant vapor after it has completely boiled into a gas is known as:

Flashing
Subcooling
Condensation
Superheating (Correct answer)

Correct answer: Superheating

Superheating is the process of raising the temperature of the refrigerant vapor above its boiling point (saturation temperature). This is a critical process to ensure that no liquid refrigerant enters and damages the compressor.

Question 38: Which of the following setup combinations will achieve the fastest and most thorough evacuation of a refrigeration system?

A 2-stage vacuum pump with large diameter (3/8" or 1/2") hoses and Schrader core removal tools. (Correct answer)
A single-stage vacuum pump with 3/8" hoses and the Schrader cores left in place.
A 2-stage vacuum pump with standard 1/4" charging hoses connected to the service ports.
A 2-stage vacuum pump with 1/4" hoses connected directly to the service valves, bypassing the manifold.

Correct answer: A 2-stage vacuum pump with large diameter (3/8" or 1/2") hoses and Schrader core removal tools.

The greatest restrictions to flow during an evacuation are the small Schrader valve openings and the small diameter of standard 1/4" hoses. Using tools to remove the Schrader cores and connecting large diameter hoses creates a much wider, less restrictive path. This allows the vacuum pump to remove moisture and non-condensables far more quickly and effectively, leading to a deeper, faster evacuation.

Question 39: Which tool is used to ensure refrigerant line sets are properly supported and do not transmit vibration into the building structure?

Tubing bender
Line set insulation
Saddle clamps
Vibration isolation hangers (Correct answer)

Correct answer: Vibration isolation hangers

Vibration isolation hangers absorb compressor vibration and prevent it from being transmitted through copper lines into walls and ceilings.

Question 40: When charging a system by weight, the technician should zero the refrigerant scale:

Before connecting the hose, with the empty hose weight accounted for (Correct answer)
After connecting the charging hose to the cylinder
After opening the cylinder valve
Only if the manufacturer requires it

Correct answer: Before connecting the hose, with the empty hose weight accounted for

Zeroing the scale with the hose already attached accounts for the hose weight, so the display shows only the refrigerant transferred rather than hose plus refrigerant.

Question 41: According to technician A, a gasket or O-ring is used to seal the system at every air conditioning connection. According to Technician B, lubricating the O-ring with the appropriate refrigerant oil before replacing it would help prevent nicks and make installation easier. Who is correct?

Both Technician A and B (Correct answer)
Neither Technician A nor B
Technician A only
Technician B only

Correct answer: Both Technician A and B

Technician A is correct because AC systems operate under high pressure and require hermetic seals to prevent refrigerant leaks, which are provided by gaskets and O-rings at every connection. Technician B is also correct; lubricating O-rings with the appropriate refrigerant oil before installation is standard practice to prevent damage like nicks or twisting during assembly, ensuring a proper and durable seal. Both practices are crucial for effective AC system repair and maintenance.

Question 42: After evacuating a system to 500 microns, a technician isolates the vacuum pump and performs a decay test. The micron gauge reading slowly rises before stabilizing at 1,500 microns. What does this most likely indicate?

The system has a large leak to the atmosphere.
The micron gauge is not calibrated correctly.
There is still moisture boiling off within the system. (Correct answer)
The vacuum pump is faulty and requires service.

Correct answer: There is still moisture boiling off within the system.

A slow rise in vacuum that eventually levels off is a classic sign of moisture remaining in the system. The moisture boils under the deep vacuum, turning into vapor and raising the pressure until all the liquid has boiled off. A large leak would cause the pressure to continue rising steadily toward atmospheric pressure.

Question 43: If the condenser fan wasn't working, what high-side and low-side pressure gauge readings might a technician discover?

High-side high and low-side low
Both high-side high and low-side are low
Both high-side high and low-side are high (Correct answer)
High-side low and low-side high

Correct answer: Both high-side high and low-side are high

If the condenser fan is not working, the condenser cannot effectively dissipate the heat from the high-pressure refrigerant. This causes the refrigerant to remain in a high-pressure, high-temperature state throughout the system, leading to abnormally high pressure readings on both the high and low sides of the system. The system struggles to cool because the heat is not being rejected to the ambient air.

Question 44: The recommended maximum lineset length without adding extra refrigerant charge for most mini-split systems is typically:

100 feet
50 feet
25 feet (pre-charged factory amount) (Correct answer)
10 feet

Correct answer: 25 feet (pre-charged factory amount)

Most mini-split systems are pre-charged at the factory for approximately 25 feet of lineset; additional refrigerant must be added for longer runs per manufacturer specs.

Question 45: A technician is searching for a very small, intermittent refrigerant leak in a system that has lost its charge over several months. Which leak detection method is generally the most effective for pinpointing such a leak?

Ultrasonic leak detector.
Halide torch detector.
Electronic (heated diode or infrared) leak detector. (Correct answer)
Soap bubble solution.

Correct answer: Electronic (heated diode or infrared) leak detector.

Electronic leak detectors, such as heated diode or infrared models, are highly sensitive and can detect refrigerant concentrations in the parts-per-million range. This makes them ideal for finding very small or intermittent leaks that are often missed by less sensitive methods like soap bubbles or ultrasonic detectors.

Question 46: Which wiring configuration connects the thermostat's Y terminal output back through the equipment to energize the contactor coil?

Y → condenser fan motor → C
Y → compressor run terminal → GND
Y → high-pressure switch → transformer primary
Y → contactor coil → C (Correct answer)

Correct answer: Y → contactor coil → C

The Y terminal signal travels through any safety switches in series, then through the contactor coil, and returns to the transformer via the C wire.

Question 47: In a properly operating refrigeration cycle, what is the state and pressure of the refrigerant as it enters the compressor?

High-pressure, high-temperature vapor
High-pressure, high-temperature liquid
Low-pressure, low-temperature liquid
Low-pressure, low-temperature superheated vapor (Correct answer)

Correct answer: Low-pressure, low-temperature superheated vapor

The refrigerant enters the compressor as a low-pressure, low-temperature superheated vapor. The evaporator's job is to absorb heat, causing the refrigerant to boil from a liquid into a vapor. Superheat is additional heat absorbed after it has fully vaporized, which ensures no liquid enters and damages the compressor.

Question 48: A compressor is wired to a 208/230V disconnect. Which wire gauge is required for a 30-amp circuit per NEC?

12 AWG
10 AWG (Correct answer)
14 AWG
8 AWG

Correct answer: 10 AWG

NEC requires 10 AWG copper conductors for a 30-amp circuit at standard ambient temperatures.

Question 49: A homeowner reports a high-pitched whistling sound coming from the supply registers, which becomes more noticeable when some vents are closed. What is the most likely cause of this noise?

The ductwork is undersized for the system's airflow.
A loose panel on the air handler cabinet is vibrating.
Excessive air velocity due to restricted outlets. (Correct answer)
The blower motor bearings are failing.

Correct answer: Excessive air velocity due to restricted outlets.

Whistling or high-pitched noises from registers are typically caused by high air velocity. When several supply registers are closed, the total airflow from the blower is forced through fewer, smaller openings. This constriction increases the speed of the air moving through the open registers and grilles, creating the whistling sound.

Question 50: A technician is charging a new residential split system that uses a capillary tube as a metering device. According to most manufacturer's guidelines, which of the following is the most accurate method for determining the correct refrigerant charge?

Adding refrigerant until the sight glass is completely clear.
Charging by weight, using the specific amount listed on the unit's data plate. (Correct answer)
Adjusting the charge to achieve a specific evaporator temperature drop (Delta T).
Charging until the suction line feels 'beer can cold'.

Correct answer: Charging by weight, using the specific amount listed on the unit's data plate.

Systems with fixed orifice metering devices, such as capillary tubes or pistons, are critically charged. The most precise and recommended method is to weigh in the exact amount of refrigerant specified by the manufacturer on the equipment's nameplate. While other methods like superheat can be used, charging by weight is the most accurate starting point for a new or fully evacuated system.

Question 51: Which tool is best suited for measuring the actual running amperage of a compressor without breaking the circuit?

Analog voltmeter
Megohmmeter
Digital capacitance meter
Clamp-on ammeter (Correct answer)

Correct answer: Clamp-on ammeter

A clamp-on ammeter measures current by sensing the magnetic field around a conductor, allowing non-invasive current measurement on live circuits.

Question 52: When brazing copper refrigerant lines, nitrogen should be flowing through the lines at what approximate pressure?

0 psig (off)
15–20 psig
2–5 psig (Correct answer)
50 psig

Correct answer: 2–5 psig

A low nitrogen purge of 2–5 psig displaces oxygen inside the tubing to prevent copper oxide scale formation without blowing out the brazing alloy.

Question 53: What is the purpose of a crankcase heater on a hermetic compressor?

Control suction superheat during low-ambient operation
Prevent refrigerant migration into the compressor oil during the off cycle (Correct answer)
Reduce starting current by warming motor windings
Pre-heat refrigerant before compression to improve efficiency

Correct answer: Prevent refrigerant migration into the compressor oil during the off cycle

A crankcase heater keeps the compressor oil warm during the off cycle, preventing liquid refrigerant from migrating into and diluting the oil.

Question 54: A homeowner reports that the AC runs constantly but never reaches the set temperature. After inspection, the technician finds the evaporator coil is clean and airflow is good. The NEXT diagnostic step should be:

Replace the thermostat immediately
Measure system operating pressures and temperatures (Correct answer)
Add refrigerant without further diagnosis
Increase blower speed

Correct answer: Measure system operating pressures and temperatures

Measuring operating pressures and temperatures provides the data needed to diagnose whether the issue is refrigerant charge, metering device, or compressor performance.

Question 55: A homeowner reports the outdoor unit runs continuously even after the thermostat setpoint is satisfied. Which component is the most likely culprit?

Welded or stuck-closed contactor contacts (Correct answer)
Open high-pressure switch
Failed start capacitor
Tripped overload protector

Correct answer: Welded or stuck-closed contactor contacts

Welded contactor contacts keep the compressor and condenser fan energized regardless of the thermostat signal.

Question 56: A system using a fixed orifice metering device shows high suction pressure in winter. What adjustment is typically required?

Add more refrigerant charge
Replace with a TXV (Correct answer)
Install a larger orifice or piston
Clean the condenser coil

Correct answer: Replace with a TXV

Fixed orifice devices cannot modulate with changing conditions; replacing with a TXV allows proper refrigerant metering across varying outdoor temperatures.

Question 57: During the final commissioning of a newly installed residential air conditioning system, which of the following checks is critical for ensuring proper equipment performance and longevity, in addition to verifying the refrigerant charge?

Verifying the thermostat brand matches the condensing unit brand.
Polishing the copper lineset for a professional appearance.
Measuring and documenting the static pressure of the duct system. (Correct answer)
Ensuring the disconnect box is aesthetically pleasing.

Correct answer: Measuring and documenting the static pressure of the duct system.

Measuring the total external static pressure (TESP) is crucial for verifying that the indoor blower is operating within its designed parameters and that the ductwork is not overly restrictive. Incorrect airflow, often indicated by high static pressure, can lead to poor performance, component failure, and inefficiency.

Question 58: A vehicle owner reports that the AC works fine in the morning but stops cooling when the outside temperature exceeds 95°F. What should be checked first?

Blower motor current draw
Refrigerant charge level and condenser airflow (Correct answer)
Thermostat opening temperature
Cabin air filter restriction

Correct answer: Refrigerant charge level and condenser airflow

High ambient temperatures stress the refrigerant system; a marginally low charge or partially blocked condenser that copes at mild temperatures will fail to reject enough heat when it is very hot outside.

Question 59: What is the primary purpose of flowing a small amount of dry nitrogen through the copper tubing while brazing a line set during an AC installation?

To prevent the formation of copper oxide scale inside the tubing (Correct answer)
To increase the internal pressure, forcing the brazing alloy into the joint
To cool the joint rapidly for a stronger bond
To purge any residual refrigerant from the new line set

Correct answer: To prevent the formation of copper oxide scale inside the tubing

When copper is heated to brazing temperatures in the presence of oxygen, a black scale (cupric oxide) forms on the interior surface of the pipe. This scale can flake off and travel through the system, potentially clogging the metering device or causing damage to the compressor. Flowing a low-pressure stream of inert dry nitrogen displaces the oxygen, preventing this oxidation from occurring.

Question 60: What problem occurs when refrigerant suction line velocities are too low in a vertical riser?

Suction pressure rises above normal
The system overcharges automatically
The metering device becomes restricted
Compressor oil fails to return and accumulates in the evaporator (Correct answer)

Correct answer: Compressor oil fails to return and accumulates in the evaporator

Oil circulates with refrigerant; insufficient velocity in vertical suction risers allows oil to drain back to the evaporator instead of returning to the compressor.

Question 61: What happens when an air conditioning system is undersized relative to the building's peak cooling load?

It operates more efficiently due to longer run times
It causes refrigerant slugging in the compressor
It short cycles and removes excess humidity
It runs continuously but cannot maintain the desired setpoint on peak days (Correct answer)

Correct answer: It runs continuously but cannot maintain the desired setpoint on peak days

An undersized system will run continuously at full capacity but still be unable to maintain the thermostat setpoint during peak outdoor design conditions.

Question 62: Which condition is indicated by oil streaks or staining around refrigerant line fittings and joints?

Normal oil migration through the system
Condensation from humidity
High oil concentration in the refrigerant
Refrigerant and oil leak at that location (Correct answer)

Correct answer: Refrigerant and oil leak at that location

Oil streaks at joints indicate refrigerant is leaking there, since refrigerant oil escapes along with refrigerant gas through any leak point.

Question 63: The following facts about an air conditioning performance test are all true, EXCEPT for

Passenger-side floor being wet is one symptom of a clogged evaporator drain line
To avoid outside odor, operate AC System in RECIRC rather than FRESH mode (Correct answer)
Obstructions of the cabin air filter may cause insufficient air circulation.
Road debris can clog the condenser fins reducing system performance

Correct answer: To avoid outside odor, operate AC System in RECIRC rather than FRESH mode

The question asks for the statement that is NOT true. Operating the AC system in RECIRC (recirculation) mode *does* help avoid outside odors by closing the fresh air intake and recirculating cabin air. Therefore, this statement is actually true, making it the incorrect answer for an 'EXCEPT' question. The other options correctly describe common AC system issues or symptoms.

Question 64: A technician finds that the vacuum gauge reads 300 microns but then rises to 1,500 microns and stabilizes. This most likely indicates:

A leak in the system
The vacuum pump oil needs changing
Moisture is present in the system (outgassing) (Correct answer)
The gauge calibration is off

Correct answer: Moisture is present in the system (outgassing)

A vacuum that rises then stabilizes at a mid-range level (not continuing to rise) indicates moisture outgassing — the water is vaporizing and raising pressure until it is pulled out.

Question 65: What safety precaution must be taken when handling R-134a refrigerant in liquid form?

Ground yourself to prevent static discharge
Wear flame-resistant gloves
Wear safety goggles and insulated gloves to prevent frostbite (Correct answer)
Use a respirator rated for organic vapors

Correct answer: Wear safety goggles and insulated gloves to prevent frostbite

Liquid R-134a evaporates rapidly on contact with skin or eyes, causing severe frostbite and injury; PPE including goggles and thermal-insulating gloves is required.

Question 66: During a service call, a technician confirms low refrigerant charge. Before adding refrigerant, the technician should:

Add refrigerant immediately to restore operation
Replace the compressor as a precaution
Locate and repair the leak first (Correct answer)
Increase the blower speed to compensate

Correct answer: Locate and repair the leak first

EPA regulations and good practice require finding and repairing leaks before recharging, as simply topping off a leaking system wastes refrigerant and is non-compliant.

Question 67: In a rectangular sheet metal duct system, what is the primary purpose of installing turning vanes inside a sharp 90-degree elbow?

To filter large debris from the airstream before a transition.
To intentionally create back-pressure for air balancing.
To reduce air turbulence and minimize static pressure loss. (Correct answer)
To increase the velocity of the air around the bend.

Correct answer: To reduce air turbulence and minimize static pressure loss.

Air has momentum and does not change direction easily. In a sharp elbow without turning vanes, air crashes into the outer wall, creating significant turbulence and a large drop in static pressure. Turning vanes are curved blades that guide the air smoothly through the turn, minimizing turbulence and the associated pressure loss, which improves overall system airflow and efficiency.

Question 68: When brazing copper refrigerant lines, nitrogen should be flowing through the tubing during the brazing process to:

Purge refrigerant oil from the line
Prevent oxidation (scaling) inside the copper tubing (Correct answer)
Speed up the cooling process after brazing
Increase braze filler flow rate

Correct answer: Prevent oxidation (scaling) inside the copper tubing

Flowing dry nitrogen through copper tubing during brazing displaces oxygen, preventing copper oxide scale formation that could contaminate the refrigerant system.

Question 69: When installing refrigerant line sets, which practice is most important to prevent future service problems?

Use the smallest tubing diameter possible to reduce cost
Run the lines in a straight line only
Document the line set route and leave accessible service ports (Correct answer)
Wrap joints with duct tape for protection

Correct answer: Document the line set route and leave accessible service ports

Documenting the line route and ensuring accessible service ports allows future technicians to diagnose and repair the system without damaging walls or ceilings.

Question 70: Before replacing a compressor, a technician should always:

Bypass the high-pressure switch
Replace only the run capacitor
Perform a system flush to remove contaminants (Correct answer)
Increase the refrigerant charge by 10%

Correct answer: Perform a system flush to remove contaminants

Flushing removes acid, moisture, and debris from a failed compressor before installing a new one, preventing premature failure of the replacement.

Question 71: What is the primary purpose of the condenser in the refrigeration cycle?

To regulate the flow of refrigerant into the evaporator.
To increase the pressure of the refrigerant vapor.
To absorb heat and boil the refrigerant.
To reject heat from the refrigerant, causing it to change from a gas to a liquid. (Correct answer)

Correct answer: To reject heat from the refrigerant, causing it to change from a gas to a liquid.

The condenser receives high-pressure, high-temperature vapor from the compressor and rejects heat to the surrounding environment (usually the outdoor air). This heat rejection causes the refrigerant to condense into a high-pressure liquid.

Question 72: A technician uses a multimeter to check the windings of a single-phase compressor motor. The readings are: Common to Run = 2 ohms, Common to Start = 6 ohms, and Run to Start = 8 ohms. A reading from any winding to the compressor casing shows infinity (OL). What do these readings indicate?

An open winding.
A shorted winding.
The motor is shorted to ground.
The motor windings are electrically sound. (Correct answer)

Correct answer: The motor windings are electrically sound.

For a single-phase motor, the resistance between the Run and Start terminals should equal the sum of the resistances from Common to Run and Common to Start (2 + 6 = 8). This confirms the windings have proper continuity. The infinity (OL) reading to the casing (ground) indicates there is no short to ground. Therefore, the windings are electrically intact.

Question 73: What is the minimum recommended vacuum level (microns) before closing service valves and charging a residential AC system?

5000 microns
500 microns (Correct answer)
1000 microns
2000 microns

Correct answer: 500 microns

Most manufacturers and industry standards require a vacuum of 500 microns or lower to ensure all moisture and non-condensables are removed.

Question 74: Which type of oil is used in systems charged with R-410A refrigerant?

Alkylbenzene oil
Polyalkylene glycol (PAG) oil
Polyol ester (POE) oil (Correct answer)
Mineral oil

Correct answer: Polyol ester (POE) oil

POE oil is required in R-410A systems because it is miscible with HFC refrigerants and properly lubricates the compressor throughout the system.

Question 75: When comparing two duct runs of the same diameter and length, which of the following will result in the highest friction loss and the greatest reduction in airflow?

A properly sized, rigid metal duct with two 45-degree elbows.
A straight run of smooth, rigid metal duct.
A properly stretched, flexible duct with one gradual 90-degree bend.
An undersized, flexible duct with several sharp bends and sagging sections. (Correct answer)

Correct answer: An undersized, flexible duct with several sharp bends and sagging sections.

Flexible ductwork has a corrugated inner liner that creates significantly more friction than smooth rigid duct. When it is also undersized for the required airflow, the velocity increases, which raises the friction loss exponentially. Adding sharp bends and allowing the duct to sag further increases turbulence and restriction, creating the worst-case scenario for airflow.

Question 76: A three-phase scroll compressor fails to start and the contactor hums but doesn't pull in fully. Which condition is most likely?

Failed run capacitor
Low 24V control voltage at the coil
Open start capacitor
Loss of one phase (single phasing) on the supply voltage (Correct answer)

Correct answer: Loss of one phase (single phasing) on the supply voltage

Single phasing causes the three-phase contactor to chatter or fail to fully pull in, and the compressor motor cannot develop starting torque on only two legs.

Question 77: A manifold gauge shows high-side pressure of 350 psi and low-side pressure of 10 psi on a hot day. What does this pattern suggest?

Normal operation
Failed condenser fan
Blocked orifice tube or expansion valve (Correct answer)
Overcharged system

Correct answer: Blocked orifice tube or expansion valve

Extremely high discharge pressure combined with very low suction pressure is a classic sign of a restriction (blockage) in the metering device, starving the evaporator of refrigerant.

Question 78: Which of the following describes the process occurring within the condenser coil?

High-pressure vapor refrigerant rejects heat and condenses into a liquid. (Correct answer)
Low-pressure liquid refrigerant boils and absorbs heat.
High-pressure liquid experiences a sharp pressure drop.
Low-pressure vapor is compressed into a high-pressure vapor.

Correct answer: High-pressure vapor refrigerant rejects heat and condenses into a liquid.

The condenser receives high-pressure, high-temperature vapor from the compressor. As outdoor air is blown across the condenser coils, the refrigerant rejects heat to the ambient air, causing it to desuperheat and then condense into a high-pressure liquid.

Question 79: During a maintenance check, the technician notices the outdoor fan motor is drawing more amps than its nameplate rating. What is the most likely cause?

Low suction pressure
Refrigerant overcharge
Dirty evaporator coil
Failing motor bearings or a failing capacitor (Correct answer)

Correct answer: Failing motor bearings or a failing capacitor

A motor drawing above nameplate amperage usually indicates worn bearings creating drag or a weak start/run capacitor failing to support the motor.

Question 80: To minimize the release of refrigerant when connecting and disconnecting gauges, EPA regulations require service hoses to be equipped with which of the following?

Color-coded grips for easy identification.
A minimum length of six feet for safety.
Brass fittings to prevent corrosion.
Low-loss fittings or shut-off valves. (Correct answer)

Correct answer: Low-loss fittings or shut-off valves.

EPA regulations under Section 608 mandate that hoses used for servicing, recovering, and charging must be equipped with low-loss fittings or valves that close automatically when the hose is disconnected. This is to trap the refrigerant within the hose and prevent it from being released into the atmosphere.

Question 81: During a new split-system installation, which of the following practices is critical for ensuring proper oil return to the compressor and preventing liquid slugging, especially with long line sets?

Ensuring the liquid line is insulated along its entire length
Using a pipe bender to create sharp 90-degree turns
Installing the suction line with a continuous downward slope from the evaporator to the condenser
Ensuring the suction line is fully insulated and properly supported (Correct answer)

Correct answer: Ensuring the suction line is fully insulated and properly supported

The suction line carries cool refrigerant gas and entrained oil back to the compressor. It must be fully insulated to prevent the gas from absorbing excess heat, which would reduce system efficiency and capacity. Proper insulation also prevents condensation from forming on the outside of the pipe. Proper support prevents sags where oil could become trapped.

Question 82: What is the recommended minimum coil cleaning frequency for a residential split-system AC under normal operating conditions?

Every 10 years
Every 5 years
Once per year (Correct answer)
Only when ice forms on the coil

Correct answer: Once per year

Evaporator and condenser coils should be cleaned at least once per year to prevent dirt buildup that reduces heat transfer.

Question 83: What is the purpose of a ground fault circuit interrupter (GFCI) outlet required near HVAC equipment in some installations?

To trip when current imbalance between hot and neutral exceeds ~5 mA, preventing shock (Correct answer)
To replace the need for an equipment disconnect
To regulate voltage to the blower motor
To prevent voltage spikes from damaging the control board

Correct answer: To trip when current imbalance between hot and neutral exceeds ~5 mA, preventing shock

A GFCI detects small current imbalances caused by current flowing through an unintended path (like a person) and opens the circuit within milliseconds.

Question 84: What is the purpose of the 'decay test' (also called a 'rise test') performed after reaching target vacuum?

To verify system tightness by monitoring micron levels after pump isolation (Correct answer)
To check electrical continuity of the compressor
To measure refrigerant charge weight
To test the expansion valve at low pressure

Correct answer: To verify system tightness by monitoring micron levels after pump isolation

After isolating the vacuum pump, micron levels are monitored for 15–30 minutes; a stable reading confirms system integrity, while a rise indicates leaks or moisture.

Question 85: What is the recommended method for testing a newly brazed joint for leaks before evacuating and charging a system?

Pressurize with nitrogen and use electronic leak detector or soap bubbles (Correct answer)
Apply a vacuum and watch the gauge
Visual inspection only
Pressurize with refrigerant to 150 psig

Correct answer: Pressurize with nitrogen and use electronic leak detector or soap bubbles

Nitrogen pressure testing with an electronic detector or soap bubbles is safe and code-compliant; using refrigerant for leak testing wastes refrigerant and is prohibited.

Question 86: What is the purpose of a suction line accumulator in a refrigeration system?

Prevent liquid refrigerant from entering the compressor (Correct answer)
Remove moisture from the refrigerant
Separate oil from the refrigerant
Store extra refrigerant charge

Correct answer: Prevent liquid refrigerant from entering the compressor

A suction line accumulator catches any liquid refrigerant before it can reach the compressor, protecting it from liquid slugging damage.

Question 87: A residential AC system's SEER2 rating is used to measure what?

Seasonal cooling efficiency over an entire cooling season under varied conditions (Correct answer)
Compressor discharge temperature
Static pressure loss across the duct system
Refrigerant recovery rate

Correct answer: Seasonal cooling efficiency over an entire cooling season under varied conditions

SEER2 (Seasonal Energy Efficiency Ratio 2) measures average cooling efficiency across a full season under a range of temperature conditions using updated test procedures.

Question 88: What does the ventilation load component account for in an HVAC load calculation?

Static pressure drop across the air handler
Air movement losses through supply and return ductwork
The energy required to size supply and return registers
Conditioning intentionally introduced outdoor fresh air (Correct answer)

Correct answer: Conditioning intentionally introduced outdoor fresh air

The ventilation load accounts for the sensible and latent energy required to condition the fresh outdoor air that is intentionally introduced into the building to meet indoor air quality standards.

Question 89: If a compressor's internal overload protects it from overheating but the unit starts immediately after being reset manually, what concern exists?

The overload is too sensitive
The refrigerant charge is too high
The run capacitor is oversized
The underlying cause of overheating was not corrected and the compressor will trip again (Correct answer)

Correct answer: The underlying cause of overheating was not corrected and the compressor will trip again

Resetting an overload without diagnosing and correcting the root cause (e.g., low refrigerant, dirty coils, high ambient) will result in repeated tripping.

Question 90: What does TXV stand for in an automotive AC system, and what is its function?

Turbo Exhaust Valve — manages backpressure
Total Vent Exchange — controls cabin air circulation
Thermal Expansion Valve — meters refrigerant flow into the evaporator (Correct answer)
Temperature eXchange Ventilator — regulates condenser temperature

Correct answer: Thermal Expansion Valve — meters refrigerant flow into the evaporator

The Thermal Expansion Valve (TXV) regulates the amount of refrigerant entering the evaporator based on evaporator outlet temperature, optimizing efficiency.

Question 91: Which of the following electrical safety devices is designed to open the control circuit and shut down the compressor in the event of a restricted condenser coil or a failed condenser fan motor?

A time-delay relay
A high-pressure safety switch (Correct answer)
A low-pressure cutout switch
A crankcase heater

Correct answer: A high-pressure safety switch

A high-pressure safety switch monitors the refrigerant discharge pressure. Conditions like a dirty condenser coil or a failed condenser fan motor prevent proper heat rejection, causing a rapid and dangerous increase in head pressure. The high-pressure switch is designed to detect this rise and open the 24V control circuit to the compressor contactor, stopping the compressor to prevent serious damage.

Question 92: A scroll compressor is running backwards due to incorrect wiring. What symptom will the technician observe?

High suction and high discharge pressure
Low suction pressure and no discharge pressure
Normal pressures but loud vibration
Very low discharge pressure and high suction pressure with loud noise (Correct answer)

Correct answer: Very low discharge pressure and high suction pressure with loud noise

A scroll compressor running in reverse produces very little compression, resulting in near-equal and abnormal pressures and often a distinctive noise.

Question 93: A technician measures superheat at the evaporator outlet and finds it excessively high. What does this indicate about the TXV?

TXV is stuck closed or restricted, starving the evaporator (Correct answer)
System is overcharged
Condenser is oversized
TXV is stuck open, flooding the evaporator

Correct answer: TXV is stuck closed or restricted, starving the evaporator

High superheat means refrigerant is fully evaporated well before the evaporator outlet, indicating insufficient refrigerant flow from a restricted or malfunctioning TXV.

Question 94: A technician installs a new 2-ton split system and finds the existing ductwork was designed for a 1.5-ton system. What is the most likely result?

Higher static pressure, reduced airflow, poor efficiency and comfort (Correct answer)
Faster system response time
Reduced refrigerant charge requirement
Improved comfort due to higher airflow

Correct answer: Higher static pressure, reduced airflow, poor efficiency and comfort

Undersized ductwork increases external static pressure, restricts airflow, reduces system efficiency, and can cause the evaporator coil to freeze.

Question 95: What does EER (Energy Efficiency Ratio) measure in an air conditioning system?

Refrigerant charge level relative to system capacity
Airflow rate through the duct system
The ratio of supply air temperature to return air temperature
Cooling output in BTU/h divided by power input in watts at a single operating condition (Correct answer)

Correct answer: Cooling output in BTU/h divided by power input in watts at a single operating condition

EER is the ratio of cooling capacity (BTU/h) to electrical power input (watts) measured at a specific set of conditions, such as 95°F outdoor and 80°F indoor.

Question 96: A technician is preparing to evacuate a system after a major repair. Before starting the vacuum pump, it is critical to:

Change the oil in the vacuum pump.
Install a new filter-drier.
Warm the refrigerant in the system to vaporize any liquid.
Ensure the system pressure is at 0 psig or below. (Correct answer)

Correct answer: Ensure the system pressure is at 0 psig or below.

A vacuum pump is designed to remove air and non-condensables from a system at very low pressures; it is not a recovery machine. Connecting a vacuum pump to a pressurized system can damage the pump and cause an illegal release of refrigerant into the atmosphere.

Question 97: What unit is commonly used to measure the cooling capacity of an air conditioning system?

Horsepower
Kilowatts
BTU/hr (Correct answer)
Watts

Correct answer: BTU/hr

BTU/hr (British Thermal Units per hour) is the standard unit used to express the cooling capacity of air conditioning equipment on nameplates and specifications.

Question 98: A home requires 36,000 BTU/hr of cooling capacity. What is the correct equipment size in tons?

2 tons
2.5 tons
3 tons (Correct answer)
3.5 tons

Correct answer: 3 tons

Dividing 36,000 BTU/hr by 12,000 BTU/hr per ton equals 3 tons, which is the correct equipment size for this load.

Question 99: To get an accurate measurement of a system's Total External Static Pressure (TESP), where should the two test probes of a manometer be placed?

Immediately before the blower wheel and immediately after the blower wheel.
In the supply plenum after the indoor coil and in the return plenum before the filter.
In the supply plenum after the indoor coil and in the return plenum after the filter but before the blower. (Correct answer)
In the return grille and in the furthest supply register.

Correct answer: In the supply plenum after the indoor coil and in the return plenum after the filter but before the blower.

Total External Static Pressure (TESP) measures the total resistance the blower motor must work against that is *external* to the air handler or furnace cabinet. This includes the supply and return ductwork. The correct measurement points are on the supply side after all internal components (like the coil or heat exchanger) and on the return side before the blower, but after the filter (as the filter is considered part of the external system resistance).

Question 100: The fundamental principle of the refrigeration cycle is based on which thermodynamic concept?

Heat naturally flows from a colder substance to a warmer substance.
Heat is created by compressing a gas and destroyed by expanding it.
Subcooling and superheating must always be equal for proper operation.
The relationship between a fluid's pressure and its boiling point. (Correct answer)

Correct answer: The relationship between a fluid's pressure and its boiling point.

The refrigeration cycle works by manipulating the refrigerant's pressure. By lowering the pressure in the evaporator, its boiling point drops, allowing it to absorb heat. By increasing the pressure in the condenser, its boiling point rises, allowing it to release heat to the warmer outdoor air. This pressure-temperature relationship is key.

HVAC/R Certification Exam

The HVAC/R Certification Exam exam validates essential knowledge and skills required for certification or licensure in this field.

100

Questions

120 min

Time Limit

70%

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