RSES Certifications (e.g., CM, CMS, RM, SM) — Questions and Answers

Question 1: A hermetic compressor motor draws locked-rotor amperage (LRA) of 45A. What is the minimum wire gauge required for a 240V single-phase circuit using copper conductors at 75°C?

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

Correct answer: 10 AWG

LRA × 1.25 = 56.25A; 10 AWG copper at 75°C is rated for 35A continuous, but NEC 440.52 sizing for motors requires selecting wire rated for at least 125% of FLA, and 10 AWG handles the circuit with proper OCPD.

Question 2: The suction line accumulator is designed to protect the compressor from:

Excessive subcooling
Liquid refrigerant slugging (Correct answer)
Oil foaming at startup
High discharge temperatures

Correct answer: Liquid refrigerant slugging

An accumulator collects liquid refrigerant and oil before the compressor inlet, releasing only vapor to prevent hydraulic damage.

Question 3: Which of the following would cause a TXV to hunt (cycle open and closed rapidly)?

Oversized TXV for the system load (Correct answer)
Correct superheat setting
Proper bulb insulation
Correct refrigerant charge

Correct answer: Oversized TXV for the system load

An oversized TXV over-responds to load changes, causing hunting as it continually opens too far then closes too far.

Question 4: Which documentation is essential when working with compressor systems in RSES?

Marketing materials
General descriptions without specifics
Detailed technical specifications and as-built diagrams (Correct answer)
Only verbal notes

Correct answer: Detailed technical specifications and as-built diagrams

Detailed technical specifications and as-built diagrams provide the accurate reference information needed for maintenance and troubleshooting.

Question 5: How should refrigerant be recovered during repairs?

Vent to air
Use recovery machine (Correct answer)
Store in cans
Dump in water

Correct answer: Use recovery machine

Use certified recovery equipment to prevent environmental damage.

Question 6: What is the best practice for maintaining condenser systems performance over time?

Outsource all maintenance
Wait for failures before acting
Upgrade all equipment annually
Implement scheduled preventive maintenance (Correct answer)

Correct answer: Implement scheduled preventive maintenance

Scheduled preventive maintenance catches potential issues before they cause failures, maintaining reliability and extending equipment life.

Question 7: Which device protects the system from electrical overload?

Pressure switch
Thermostat
Fuse or breaker (Correct answer)
Relay

Correct answer: Fuse or breaker

A fuse or circuit breaker cuts off current when it exceeds safe limits.

Question 8: A filter-drier in a refrigeration system is primarily installed to:

Increase system capacity
Remove moisture and contaminants from the refrigerant (Correct answer)
Cool the discharge gas
Regulate refrigerant flow rate

Correct answer: Remove moisture and contaminants from the refrigerant

Filter-driers adsorb moisture and trap particulates to protect the expansion device and compressor from damage.

Question 9: Subcooling in a refrigeration system refers to cooling the liquid refrigerant:

Above its condensing temperature
To the suction saturation temperature
Below its condensing temperature (Correct answer)
To its boiling point in the evaporator

Correct answer: Below its condensing temperature

Subcooling lowers liquid refrigerant temperature below its saturation point, preventing flash gas before the expansion device.

Question 10: During installation of a parallel compressor rack, why are unloaders or capacity steps typically required on individual compressors?

To reduce electrical starting current below panel capacity
To synchronize compressor rotation speeds
To allow staged capacity matching to varying load conditions and prevent short cycling (Correct answer)
To prevent compressor overheating during summer operation

Correct answer: To allow staged capacity matching to varying load conditions and prevent short cycling

Capacity control via unloaders or staging allows the rack to match refrigeration output to varying load, preventing short cycling and improving efficiency across different operating conditions.

Question 11: During a compressor replacement, you discover the old compressor failed due to a flooded start. What maintenance step should be added going forward?

Install a desuperheater
Replace the metering device with a larger orifice
Install a suction line accumulator (Correct answer)
Add a hot gas bypass valve

Correct answer: Install a suction line accumulator

A suction line accumulator prevents liquid refrigerant from entering the compressor during startup, protecting against flooded starts.

Question 12: What effect does increasing the length of a capillary tube have on system performance?

Has no effect on flow rate
Increases evaporator pressure
Increases refrigerant flow rate
Decreases refrigerant flow rate (Correct answer)

Correct answer: Decreases refrigerant flow rate

A longer capillary tube increases friction resistance, reducing refrigerant flow rate and lowering evaporator pressure.

Question 13: Why is PPE important in refrigeration work?

To keep uniforms clean
To store tools
For identification
To protect from hazards (Correct answer)

Correct answer: To protect from hazards

It protects technicians from chemical, electrical, and physical hazards.

Question 14: Technician A says superheat should be measured at the evaporator outlet. Technician B says superheat should be measured at the compressor inlet. Who is correct?

Neither technician
Technician A only
Both technicians, depending on what is being measured (Correct answer)
Technician B only

Correct answer: Both technicians, depending on what is being measured

Evaporator superheat is measured at the evaporator outlet for TXV adjustment, while total (compressor) superheat is measured at the compressor inlet for overall system evaluation.

Question 15: An electronic expansion valve (EEV) in a variable refrigerant flow (VRF) system is typically controlled by:

A manual pressure regulator
Direct high-side pressure feedback only
A microprocessor receiving inputs from multiple sensors (Correct answer)
A mechanical sensing bulb

Correct answer: A microprocessor receiving inputs from multiple sensors

EEVs in VRF systems are controlled by microprocessors using inputs such as suction superheat, coil temperature, and load demand for optimal performance.

Question 16: Which device controls the refrigerant flow into the evaporator?

TXV (Correct answer)
Accumulator
Solenoid coil
Filter-drier

Correct answer: TXV

The TXV, or Thermostatic Expansion Valve, is a crucial component that controls the flow of liquid refrigerant into the evaporator. It meters the amount of refrigerant based on the superheat of the refrigerant vapor leaving the evaporator, ensuring optimal cooling and preventing liquid refrigerant from returning to the compressor. This precise control maximizes system efficiency.

Question 17: Which preventive maintenance approach is MOST effective for RSES professionals managing equipment?

Schedule regular maintenance based on manufacturer recommendations and usage patterns (Correct answer)
Fix equipment only when it breaks down
Perform maintenance annually regardless of usage
Outsource all maintenance to reduce internal workload

Correct answer: Schedule regular maintenance based on manufacturer recommendations and usage patterns

Scheduling maintenance based on manufacturer recommendations and actual usage patterns optimizes equipment reliability and lifespan. This approach prevents unexpected breakdowns while avoiding unnecessary maintenance on lightly used equipment.

Question 18: A technician notices the suction line is sweating all the way back to the compressor. What does this indicate about evaporator performance?

The evaporator is flooding or overfeeding refrigerant, with liquid returning in the suction line (Correct answer)
The evaporator fan has failed, reducing heat transfer
The system refrigerant charge is low
The evaporator superheat is too high, indicating a starved coil

Correct answer: The evaporator is flooding or overfeeding refrigerant, with liquid returning in the suction line

Sweating along the entire suction line indicates liquid refrigerant is present in the suction gas, a sign of evaporator flooding or a failed TXV.

Question 19: Which refrigerant is known for being environmentally friendly?

Ammonia
R-22
R-134a (Correct answer)
R-11

Correct answer: R-134a

R-134a (tetrafluoroethane) is a hydrofluorocarbon (HFC) refrigerant widely used in automotive air conditioning, domestic refrigerators, and chillers. It is considered more environmentally friendly than older refrigerants like R-22 because it has zero ozone depletion potential (ODP). While it does have a global warming potential (GWP), it's a common choice for its balance of performance and environmental impact.

Question 20: Which component compresses the refrigerant gas in a system?

Evaporator
Thermostat
Compressor (Correct answer)
Condenser

Correct answer: Compressor

The compressor is often considered the 'heart' of a refrigeration system. Its primary function is to draw in low-pressure, low-temperature refrigerant vapor from the evaporator and compress it into a high-pressure, high-temperature gas. This compression is essential for raising the refrigerant's temperature and pressure, allowing it to release heat in the condenser.

Question 21: What is meant by the term 'static superheat' in a TXV?

Superheat measured at maximum load
Superheat measured during system shutdown
The superheat setting due to spring tension alone when bulb and evaporator pressures are equal (Correct answer)
The superheat caused by ambient temperature effects

Correct answer: The superheat setting due to spring tension alone when bulb and evaporator pressures are equal

Static superheat is established by the valve spring's initial tension and represents the minimum superheat before the valve begins to open.

Question 22: Which type of expansion device is most commonly used in small hermetic refrigeration systems like household refrigerators?

Electronic expansion valve
Capillary tube (Correct answer)
Float valve
Thermostatic expansion valve

Correct answer: Capillary tube

Capillary tubes are inexpensive, have no moving parts, and are well-suited to fixed-load applications like household refrigerators.

Question 23: What role does the evaporator play in the refrigeration cycle?

Produces electricity
Stores liquid
Absorbs heat (Correct answer)
Condenses refrigerant

Correct answer: Absorbs heat

In the refrigeration cycle, the evaporator's main role is to absorb heat from the space or substance being cooled. As the low-pressure liquid refrigerant enters the evaporator, it boils and changes into a vapor by absorbing latent heat from its surroundings. This phase change is what produces the cooling effect.

Question 24: What is the MOST important reason for maintaining equipment maintenance logs in RSES practice?

To assign blame when equipment fails
To track maintenance history, predict failures, and demonstrate compliance (Correct answer)
To justify equipment replacement budgets
To satisfy insurance requirements only

Correct answer: To track maintenance history, predict failures, and demonstrate compliance

Equipment maintenance logs serve multiple critical purposes: tracking maintenance history allows for trend analysis, predicting potential failures enables preventive action, and documented maintenance demonstrates regulatory compliance.

Question 25: What is the recommended first step when a RSES professional identifies a compliance violation?

Wait for someone else to report it
Ignore it if minor
Document and report through proper channels (Correct answer)
Discuss on social media

Correct answer: Document and report through proper channels

All compliance violations should be documented and reported through established channels to ensure proper investigation and resolution.

Question 26: Which factor MOST significantly affects the quality of technical outcomes in RSES practice?

The speed at which procedures are completed
The time of day the procedure is performed
The brand of equipment being used
The practitioner's training, preparation, and attention to detail (Correct answer)

Correct answer: The practitioner's training, preparation, and attention to detail

The quality of technical outcomes depends primarily on the practitioner's level of training, thorough preparation, and careful attention to detail. While equipment matters, the professional's competence is the most significant factor.

Question 27: A technician is retrofitting an R-22 system to R-407C. Which oil change is required?

Polyol ester (POE) oil must replace mineral oil (Correct answer)
Mineral oil can remain if system is clean
Polyalkylene glycol (PAG) oil must replace mineral oil
Alkylbenzene (AB) oil must be added

Correct answer: Polyol ester (POE) oil must replace mineral oil

R-407C is an HFC refrigerant that requires POE oil because it is miscible with HFCs, whereas mineral oil is not compatible and must be removed.

Question 28: A three-phase compressor motor is running but drawing unequal current on the three legs. The most likely cause is:

Overcharged refrigerant system
Voltage imbalance or open motor winding (Correct answer)
Defective crankcase heater
Shorted run capacitor

Correct answer: Voltage imbalance or open motor winding

Current imbalance in a three-phase motor typically indicates either a supply voltage imbalance or a partially shorted/open winding, both of which cause unequal current draw per phase.

Question 29: What is the PROPER procedure for decommissioning outdated equipment in Refrigeration Service Engineers Society Certification practice?

Simply discard it in regular waste disposal
Donate it without any preparation or documentation
Store it indefinitely in case it might be needed
Follow established protocols for safe decommissioning, data clearing, and proper disposal (Correct answer)

Correct answer: Follow established protocols for safe decommissioning, data clearing, and proper disposal

Equipment decommissioning requires following established protocols that may include safe shutdown procedures, clearing any stored data, proper disposal of hazardous components, documentation of the decommissioning, and compliance with environmental regulations.

Question 30: What is the correct procedure when brazing a copper-to-brass fitting joint in a refrigeration system?

Heat the brass fitting exclusively to avoid copper oxidation
Use soft solder (50/50 tin-lead) for maximum flow
Use silver alloy filler with appropriate flux on the brass side (Correct answer)
Use BCuP filler metal without flux

Correct answer: Use silver alloy filler with appropriate flux on the brass side

When brazing copper-to-brass, silver alloy filler (phos-copper works on copper but requires flux on brass) with appropriate flux on the brass side is required to prevent oxidation and ensure proper bonding.

Question 31: What happens in the condenser unit?

Expands gas
Absorbs moisture
Blocks airflow
Releases heat and condenses (Correct answer)

Correct answer: Releases heat and condenses

In the condenser unit, the high-pressure, high-temperature refrigerant gas, which absorbed heat in the evaporator, releases that heat to the cooler ambient air or water. As it loses heat, the refrigerant changes state from a gas back into a high-pressure liquid. This process is essential for completing the refrigeration cycle and dissipating the absorbed heat.

Question 32: What type of heat transfer occurs in a refrigeration system?

Conduction, convection, and radiation (Correct answer)
Only radiation
Magnetic force
Only conduction

Correct answer: Conduction, convection, and radiation

All three primary modes of heat transfer—conduction, convection, and radiation—occur within a refrigeration system. Conduction transfers heat through direct contact (e.g., refrigerant through copper tubing), convection involves heat transfer through fluid movement (e.g., air circulating over coils), and radiation transfers heat via electromagnetic waves (e.g., heat radiating from a condenser coil). The system is designed to manage these transfers efficiently.

Question 33: What is the purpose of a suction line accumulator installed between the evaporator and compressor?

To increase suction gas superheat beyond TXV settings
To filter oil out of the suction gas
To store extra refrigerant during low-load conditions
To prevent liquid refrigerant slugs from reaching the compressor (Correct answer)

Correct answer: To prevent liquid refrigerant slugs from reaching the compressor

A suction line accumulator traps liquid refrigerant and oil, releasing only vapor to the compressor to prevent liquid slugging damage.

Question 34: When installing a refrigeration system in a machinery room, which code requirement governs the minimum ventilation rate?

ASHRAE Standard 15 specifies ventilation based on refrigerant quantity and room volume (Correct answer)
OSHA 1910.119 specifies ventilation for all refrigerants above 100 lbs
NEC Article 440 specifies minimum airflow in CFM per compressor horsepower
EPA Section 608 specifies ventilation for all refrigerant types

Correct answer: ASHRAE Standard 15 specifies ventilation based on refrigerant quantity and room volume

ASHRAE Standard 15 (Safety Standard for Refrigeration Systems) provides the formula and requirements for machinery room ventilation rates based on refrigerant type and quantity.

Question 35: Why must circuit diagrams be followed?

To draw pictures
Ensure proper wiring (Correct answer)
Label refrigerant
To replace fuses

Correct answer: Ensure proper wiring

They provide the correct wiring and operation layout.

Question 36: What is the most important professional competency for RSES certification in expansion devices?

Memorization of all reference materials
Speed of task completion
Ability to work alone exclusively
Deep knowledge combined with practical application skills (Correct answer)

Correct answer: Deep knowledge combined with practical application skills

Professional competency requires both deep knowledge of the subject matter and the ability to apply that knowledge in practical situations.

Question 37: Which approach best describes risk-based compliance management in the RSES field?

Eliminating all possible risks
Focusing only on past incidents
Treating all risks equally
Prioritizing resources based on risk severity and likelihood (Correct answer)

Correct answer: Prioritizing resources based on risk severity and likelihood

Risk-based compliance management involves assessing and prioritizing risks by their severity and likelihood to allocate resources effectively.

Question 38: Why must electrical connections be checked during repairs?

To increase vibration
To reduce brightness
To reduce humidity
To ensure safe operation (Correct answer)

Correct answer: To ensure safe operation

Loose or corroded connections can cause equipment failure.

Question 39: A direct-expansion evaporator serving a walk-in cooler shows adequate airflow but poor temperature pull-down. The suction pressure is normal. What is the most likely cause?

Dirty evaporator coil fins (Correct answer)
Faulty condenser fan
Low ambient temperature
Overcharged system

Correct answer: Dirty evaporator coil fins

Dirty or frosted fins restrict heat transfer between the air and refrigerant even when airflow volume appears adequate, reducing the effective cooling capacity.

Question 40: What is the purpose of performing a triple evacuation during system commissioning?

To progressively remove moisture and non-condensables by alternating vacuum and dry nitrogen breaks (Correct answer)
To test the system for leaks at elevated pressure
To flush contaminants out with refrigerant vapor
To remove all refrigerant charge before servicing

Correct answer: To progressively remove moisture and non-condensables by alternating vacuum and dry nitrogen breaks

Triple evacuation uses alternating deep vacuum pulls and dry nitrogen breaks to progressively dilute and remove moisture and non-condensables more effectively than a single evacuation.

Question 41: What is the PRIMARY purpose of obtaining RSES certification in Refrigeration Service Engineers Society Certification?

To bypass educational requirements
To demonstrate verified competency and adherence to professional standards (Correct answer)
To guarantee employment in the field
To satisfy a personal achievement goal

Correct answer: To demonstrate verified competency and adherence to professional standards

Professional certification demonstrates that an individual has met established competency standards through verified assessment. It provides assurance to employers, clients, and the public that the certified professional possesses the knowledge and skills required for competent practice.

Question 42: How often should RSES compliance training be conducted?

Only when violations occur
Every five years
Only during initial orientation
At regular intervals as required by regulations (Correct answer)

Correct answer: At regular intervals as required by regulations

Compliance training must be conducted at regular intervals as specified by applicable regulations to keep practitioners current.

Question 43: Which approach is MOST important for RSES professionals when applying technical procedures?

Following personal shortcuts developed through experience
Applying the same technique in every situation without variation
Adhering to established protocols while adapting to specific conditions (Correct answer)
Using the fastest method available regardless of standards

Correct answer: Adhering to established protocols while adapting to specific conditions

Technical procedures require adherence to established protocols as a foundation, with professional judgment to adapt appropriately to specific conditions. This balance ensures both consistency and effectiveness.

Question 44: In RSES practice, what is the best approach to quality improvement in expansion devices?

Use data-driven methods with measurable outcomes (Correct answer)
Make changes without measuring results
Copy what other organizations do without analysis
Wait for problems to occur before acting

Correct answer: Use data-driven methods with measurable outcomes

Data-driven quality improvement with measurable outcomes ensures that changes actually produce the intended improvements and can be verified.

Question 45: What role does documentation play in RSES compliance?

It provides evidence of adherence to standards (Correct answer)
It is optional
It is only needed for audits
It replaces practical competency

Correct answer: It provides evidence of adherence to standards

Documentation provides verifiable evidence that standards and regulations are being followed, serving as proof of compliance.

Question 46: When new equipment is introduced in a Refrigeration Service Engineers Society Certification setting, what is REQUIRED before staff members use it?

Reading the equipment manual independently
Watching a colleague use it once
Formal training, competency verification, and documentation of training completion (Correct answer)
A brief verbal overview is sufficient

Correct answer: Formal training, competency verification, and documentation of training completion

New equipment requires formal training that covers safe operation, potential hazards, and proper procedures. Staff competency must be verified through assessment, and training completion must be documented for compliance and accountability.

Question 47: What role does collaboration play in troubleshooting for RSES professionals?

It slows down work unnecessarily
It is only needed in emergencies
It enhances outcomes through diverse perspectives and shared expertise (Correct answer)
It reduces individual accountability

Correct answer: It enhances outcomes through diverse perspectives and shared expertise

Collaboration leverages diverse perspectives and combined expertise to achieve better outcomes than any individual could alone.

Question 48: A technician needs to braze a refrigerant line while it is still pressurized with nitrogen. What is the correct procedure?

Maintain 2–3 PSIG nitrogen flow through the line while brazing to prevent oxidation scaling (Correct answer)
Reduce nitrogen pressure to below 5 PSI and braze normally
Purge nitrogen completely before brazing, then re-pressurize afterward
Brazing on a pressurized line is never permitted; the line must be fully evacuated first

Correct answer: Maintain 2–3 PSIG nitrogen flow through the line while brazing to prevent oxidation scaling

Industry best practice is to flow dry nitrogen at 2–3 PSIG through the line while brazing to prevent internal oxidation (black scale) that can contaminate the refrigeration system.

Question 49: What is the purpose of leak testing during installation?

To test noise levels
To clean the compressor
To detect refrigerant leaks (Correct answer)
To verify gas mileage

Correct answer: To detect refrigerant leaks

To identify and fix any refrigerant leaks for safe operation.

Question 50: What does the EPA Section 608 certification cover?

Electrical installations
Plumbing repairs
Refrigerant handling rules (Correct answer)
Tool calibration

Correct answer: Refrigerant handling rules

The EPA Section 608 certification is a federal requirement for technicians who work with refrigerants. It covers the proper handling, recovery, recycling, and reclaiming of refrigerants to prevent their release into the atmosphere. This is crucial because refrigerants are potent greenhouse gases and ozone-depleting substances.

Question 51: Which approach is MOST important for RSES professionals when applying technical procedures?

Using the fastest method available regardless of standards
Applying the same technique in every situation without variation
Adhering to established protocols while adapting to specific conditions (Correct answer)
Following personal shortcuts developed through experience

Correct answer: Adhering to established protocols while adapting to specific conditions

Question 52: Which type of overload relay automatically resets after cooling down without requiring manual intervention?

Manual-reset bimetallic relay
Magnetic overload relay
Auto-reset bimetallic relay (Correct answer)
Fuse-type overload

Correct answer: Auto-reset bimetallic relay

An auto-reset bimetallic overload relay restores the circuit automatically once the bimetal strip cools and returns to its original position.

Question 53: A technician finds that a newly commissioned system has high discharge superheat (greater than 75°F above condensing temperature). What is the most likely cause?

Low refrigerant charge or refrigerant restriction (Correct answer)
Condenser fan cycling on too frequently
Refrigerant overcharge
Low evaporator airflow

Correct answer: Low refrigerant charge or refrigerant restriction

Excessively high discharge superheat typically indicates low refrigerant charge or a restriction starving the compressor of suction vapor, causing gas to superheat more than normal.

Question 54: What is the primary function of a thermostatic expansion valve (TXV) in a refrigeration system?

Meter refrigerant flow to maintain superheat at the evaporator outlet (Correct answer)
Remove heat from the condenser
Separate liquid and vapor refrigerant
Compress the refrigerant to high pressure

Correct answer: Meter refrigerant flow to maintain superheat at the evaporator outlet

A TXV meters refrigerant flow into the evaporator to maintain a set superheat, preventing liquid slugging at the compressor.

Question 55: Which factor most significantly affects the air-side heat transfer performance of a fin-and-tube evaporator?

Tube material (copper vs. aluminum)
Number of refrigerant circuits
Fin spacing and fin surface cleanliness (Correct answer)
Refrigerant type used in the tubes

Correct answer: Fin spacing and fin surface cleanliness

Fin spacing determines airflow resistance and surface area, while cleanliness ensures that the full fin surface area is available for heat exchange.

Question 56: In a refrigeration control circuit, a normally open (NO) pressure switch closes at 250 psig and opens at 300 psig. This switch is functioning as a:

High-pressure safety cutout
High-pressure operating control (Correct answer)
Low-pressure operating control
Low-pressure safety cutout

Correct answer: High-pressure operating control

A switch that closes on pressure rise and opens at a high setpoint is a high-pressure operating control, cycling the system to maintain discharge pressure within a range.

Question 57: What is the purpose of the MOP (Maximum Operating Pressure) feature in some TXVs?

To prevent the evaporator pressure from exceeding a set maximum during pulldown (Correct answer)
To regulate refrigerant charge quantity
To limit compressor discharge pressure
To control condenser fan cycling

Correct answer: To prevent the evaporator pressure from exceeding a set maximum during pulldown

MOP prevents the TXV from opening fully during high-load pulldown conditions, protecting the compressor motor from overloading.

Question 58: What routine maintenance is required for air filters?

Lubricate them
Paint them
Freeze them
Replace or clean periodically (Correct answer)

Correct answer: Replace or clean periodically

They should be cleaned or replaced regularly to ensure airflow.

Question 59: Which tool is commonly used for brazing refrigerant lines?

Heat gun
Vacuum pump
Oxy-acetylene torch (Correct answer)
Pliers

Correct answer: Oxy-acetylene torch

An oxy-acetylene torch is used to weld or braze copper tubing.

Question 60: A scroll compressor is running but producing no cooling. Suction and discharge pressures are nearly equal. What is the most likely cause?

Low refrigerant charge
High superheat at the evaporator
Scroll compressor running in reverse rotation (Correct answer)
Plugged liquid line filter-drier

Correct answer: Scroll compressor running in reverse rotation

Scroll compressors rotating in the wrong direction (reverse rotation) will run but fail to build pressure differential, resulting in near-equal suction and discharge pressures.

Question 61: Which factor primarily determines the refrigerant flow capacity of a capillary tube?

Tube length and inside diameter (Correct answer)
Tube material composition
Ambient temperature only
Refrigerant color and viscosity

Correct answer: Tube length and inside diameter

Capillary tube flow capacity is determined by its length and inside diameter, with shorter/larger diameter tubes passing more refrigerant.

Question 62: Which NEC article specifically governs the installation of air-conditioning and refrigerating equipment?

Article 450
Article 440 (Correct answer)
Article 430
Article 460

Correct answer: Article 440

NEC Article 440 covers air-conditioning and refrigerating equipment, including hermetic refrigerant motor-compressors and their associated electrical circuits.

Question 63: What does a megohmmeter (megger) primarily measure in refrigeration system electrical diagnostics?

Insulation resistance of motor windings (Correct answer)
Voltage drop across windings
Capacitance of run capacitors
Continuity of control circuit fuses

Correct answer: Insulation resistance of motor windings

A megohmmeter applies high DC voltage (typically 500–1000V) to measure insulation resistance in megohms, revealing winding degradation or moisture ingress.

Question 64: What is the function of a contactor in a refrigeration system?

Transfer refrigerant
Measure humidity
Filter air
Control high-voltage circuits (Correct answer)

Correct answer: Control high-voltage circuits

It acts as a switch to control high-voltage components.

Question 65: Why is grounding important in electrical systems?

Prevent electrical shocks (Correct answer)
Reduce noise
Change voltage
Improve cooling

Correct answer: Prevent electrical shocks

To ensure user safety and prevent electrical shocks.

Question 66: What is the recommended first step when a RSES professional identifies a compliance violation?

Wait for someone else to report it
Discuss on social media
Document and report through proper channels (Correct answer)
Ignore it if minor

Correct answer: Document and report through proper channels

All compliance violations should be documented and reported through established channels to ensure proper investigation and resolution.

Question 67: What role does collaboration play in expansion devices for RSES professionals?

It is only needed in emergencies
It slows down work unnecessarily
It reduces individual accountability
It enhances outcomes through diverse perspectives and shared expertise (Correct answer)

Correct answer: It enhances outcomes through diverse perspectives and shared expertise

Collaboration leverages diverse perspectives and combined expertise to achieve better outcomes than any individual could alone.

Question 68: What is the role of a thermostat?

Closes ducts
Adds moisture
Moves air
Regulates temperature (Correct answer)

Correct answer: Regulates temperature

It senses temperature and controls the system accordingly.

Question 69: What is the function of the distributor nozzle connected to a TXV outlet in a multi-circuit evaporator?

It regulates superheat independently
It measures refrigerant quality
It evenly distributes refrigerant to all evaporator circuits (Correct answer)
It prevents liquid floodback

Correct answer: It evenly distributes refrigerant to all evaporator circuits

The distributor nozzle splits the refrigerant mixture from the TXV into equal portions for each evaporator circuit to ensure uniform loading.

Question 70: What is the primary advantage of an electronic expansion valve (EEV) over a TXV?

No need for a refrigerant charge
More precise refrigerant flow control across varying conditions (Correct answer)
Eliminates the need for a compressor
Lower cost and simpler installation

Correct answer: More precise refrigerant flow control across varying conditions

EEVs use electronic controls and stepper motors for precise modulation, outperforming TXVs in variable-load or multi-evaporator applications.

Question 71: Which approach best demonstrates mastery of expansion devices in RSES practice?

Following procedures without understanding
Avoiding complex scenarios
Relying entirely on technology
Applying principles to novel situations with sound judgment (Correct answer)

Correct answer: Applying principles to novel situations with sound judgment

True mastery involves understanding underlying principles well enough to apply them to new and unfamiliar situations with professional judgment.

Question 72: Why is it important to follow manufacturer specifications?

To speed repairs
To ensure performance and safety (Correct answer)
To avoid paperwork
To skip steps

Correct answer: To ensure performance and safety

To ensure proper function, warranty coverage, and safety.

Question 73: Which refrigerant property most directly determines the evaporating temperature in an evaporator operating at a fixed suction pressure?

Specific heat of the refrigerant vapor
Latent heat of vaporization
Liquid density at the inlet
Saturation temperature corresponding to that pressure (Correct answer)

Correct answer: Saturation temperature corresponding to that pressure

The evaporating temperature is the saturation temperature of the refrigerant at the prevailing suction pressure, as defined by the pressure-temperature relationship.

Question 74: What tool measures voltage and current?

Caliper
Thermometer
Multimeter (Correct answer)
Wrench

Correct answer: Multimeter

A multimeter is used to test electrical circuits.

Question 75: How should refrigerants be handled to ensure safety?

Using proper equipment and procedures (Correct answer)
By shaking the tank
In poorly ventilated areas
With bare hands

Correct answer: Using proper equipment and procedures

Use appropriate tools and follow manufacturer guidelines.

Question 76: A capacitor-start, capacitor-run (CSCR) motor fails to start but hums loudly. Which component is most likely faulty?

Start capacitor or centrifugal switch (Correct answer)
Overload protector
Main winding
Run capacitor

Correct answer: Start capacitor or centrifugal switch

Humming without starting indicates the start winding circuit is open, typically caused by a failed start capacitor or a defective centrifugal switch that won't close.

Question 77: What role does documentation play in RSES compliance?

It provides evidence of adherence to standards (Correct answer)
It is only needed for audits
It is optional
It replaces practical competency

Correct answer: It provides evidence of adherence to standards

Documentation provides verifiable evidence that standards and regulations are being followed, serving as proof of compliance.

Question 78: What is the purpose of a capacitor in a motor circuit?

Increase noise
Dim the lights
Boost motor performance (Correct answer)
Heat the coil

Correct answer: Boost motor performance

To provide a starting or running boost for motors.

Question 79: What is subcooling in refrigeration?

Warming refrigerant
Freezing coils
Insulating pipes
Cooling below condensing point (Correct answer)

Correct answer: Cooling below condensing point

Subcooling in refrigeration refers to the process of cooling the liquid refrigerant below its saturation temperature (condensing point) at a given pressure. This additional cooling occurs after the refrigerant has fully condensed in the condenser. Subcooling increases the system's efficiency by ensuring that only liquid refrigerant enters the expansion device, preventing flash gas and improving cooling capacity.

Question 80: Which tool measures refrigerant pressure in a system?

Clamp meter
Thermometer
Ohmmeter
Manifold gauge (Correct answer)

Correct answer: Manifold gauge

A manifold gauge set is a specialized tool used by HVAC/R technicians to measure the pressure of refrigerant in a system. It typically consists of two or more pressure gauges (high-side and low-side) connected to a manifold with valves and hoses. This allows technicians to accurately read system pressures, charge refrigerant, and evacuate the system.

Question 81: A clogged or restricted TXV will cause the suction pressure to:

Increase above normal
Drop below normal (Correct answer)
Remain at normal operating pressure
Fluctuate erratically between high and low

Correct answer: Drop below normal

A restricted TXV starves the evaporator of refrigerant, reducing suction pressure and causing abnormally low evaporator temperatures.

Question 82: In RSES certification, what does redundancy in system design primarily provide?

Fault tolerance and high availability (Correct answer)
Simplified maintenance
Lower initial cost
Increased complexity

Correct answer: Fault tolerance and high availability

Redundancy provides fault tolerance by ensuring that if one component fails, backup components maintain system availability.

Question 83: A glycol chiller evaporator shows reduced capacity but the refrigerant side readings are normal. What is the most likely cause on the glycol side?

Refrigerant overcharge flooding the evaporator
High glycol concentration reducing heat transfer and flow rate (Correct answer)
Faulty TXV allowing too much refrigerant flow
Low refrigerant superheat causing liquid slugging

Correct answer: High glycol concentration reducing heat transfer and flow rate

Excessive glycol concentration increases viscosity and reduces the glycol-side heat transfer coefficient, significantly cutting the chiller's effective capacity.

Question 84: The short-tube orifice (fixed orifice) expansion device is commonly used in which type of system?

Variable-capacity commercial refrigeration
Residential heat pumps with scroll compressors (Correct answer)
Large industrial chillers
Flooded shell-and-tube evaporators

Correct answer: Residential heat pumps with scroll compressors

Short-tube orifices are widely used in residential heat pumps because they allow bidirectional flow needed for heating and cooling mode switching.

Question 85: Which expansion device is best suited for a system with widely varying load conditions?

Automatic expansion valve
Thermostatic expansion valve (Correct answer)
Short-tube orifice
Capillary tube

Correct answer: Thermostatic expansion valve

The TXV modulates based on superheat sensing, making it ideal for systems with variable loads unlike fixed-restriction devices.

Question 86: What agency sets safety standards for refrigeration technicians in the U.S.?

OSHA (Correct answer)
FDA
EPA
DOE

Correct answer: OSHA

OSHA is responsible for workplace safety regulations.

Question 87: Which of the following is the standard unit used to express refrigeration capacity in the United States?

BTU
Kilowatt
Horsepower
Ton of refrigeration (Correct answer)

Correct answer: Ton of refrigeration

A ton of refrigeration equals 12,000 BTU/hr, and is the standard US unit for expressing refrigeration system capacity.

Question 88: Which factor MOST significantly affects the quality of technical outcomes in RSES practice?

The speed at which procedures are completed
The practitioner's training, preparation, and attention to detail (Correct answer)
The brand of equipment being used
The time of day the procedure is performed

Correct answer: The practitioner's training, preparation, and attention to detail

Question 89: A low-side float valve opens when the liquid level in the evaporator:

Reaches minimum temperature
Reaches maximum capacity
Falls below the setpoint (Correct answer)
Rises above the setpoint

Correct answer: Falls below the setpoint

When liquid level drops, the float falls and opens the valve to admit more refrigerant, maintaining the correct flooded level.

Question 90: In RSES certification, what is the primary purpose of regulatory compliance programs?

To eliminate competition
To increase revenue
To reduce staffing needs
To ensure adherence to laws and standards (Correct answer)

Correct answer: To ensure adherence to laws and standards

Regulatory compliance programs are designed to ensure organizations follow applicable laws, regulations, and standards.

Question 91: Which professional attribute is most valued in troubleshooting within the RSES field?

Avoiding challenging situations
Working in isolation
Accountability and commitment to standards (Correct answer)
Prioritizing personal convenience

Correct answer: Accountability and commitment to standards

Accountability and commitment to professional standards build trust and ensure consistent, high-quality practice.

Question 92: On a pressure-enthalpy (P-H) diagram, the horizontal distance across the evaporator represents:

Compression work input
Latent heat absorbed (refrigerating effect) (Correct answer)
Refrigerant mass flow rate
Condenser heat rejection

Correct answer: Latent heat absorbed (refrigerating effect)

The evaporator process appears as a horizontal line at low pressure; its horizontal length equals the enthalpy change, which is the refrigerating effect.

Question 93: What condition is indicated when an evaporator coil is completely blocked with ice, the box temperature is rising, yet the suction pressure is lower than normal?

The TXV is overfeeding the evaporator causing flooding
The refrigerant charge is low, starving the evaporator
The condenser is fouled, raising discharge pressure and lowering suction pressure
The ice blockage is restricting airflow, reducing heat absorption so the refrigerant cools excessively and suction pressure drops (Correct answer)

Correct answer: The ice blockage is restricting airflow, reducing heat absorption so the refrigerant cools excessively and suction pressure drops

An ice-blocked coil starves the refrigerant of heat input because air cannot reach the coil surface, causing the refrigerant to over-cool and pull suction pressure below normal.

Question 94: How is a relay used in a control system?

Switches circuits (Correct answer)
Regulates pressure
Heats the air
Cools the refrigerant

Correct answer: Switches circuits

It opens or closes circuits based on control signals.

Question 95: Which type of condenser uses ambient air blown across the coil by a fan to reject heat?

Evaporative condenser
Water-cooled shell-and-tube condenser
Double-pipe condenser
Air-cooled condenser (Correct answer)

Correct answer: Air-cooled condenser

Air-cooled condensers use fans to move ambient air over finned coils, transferring refrigerant heat directly to the air.

Question 96: What is the typical superheat setting range for a TXV used in air conditioning applications?

1-3°F
30-40°F
20-25°F
8-12°F (Correct answer)

Correct answer: 8-12°F

Most air conditioning TXVs are factory set for 8-12°F superheat to ensure full evaporator use while protecting the compressor.

Question 97: What symptom would a refrigeration technician observe if the TXV sensing bulb loses its refrigerant charge?

TXV closes fully, starving the evaporator (Correct answer)
TXV operates normally with slight superheat error
High-side pressure drops dramatically
TXV opens fully, flooding the evaporator

Correct answer: TXV closes fully, starving the evaporator

Without bulb pressure as the opening force, the spring pressure keeps the TXV closed, starving the evaporator and causing high superheat.

Question 98: Which refrigerant property is measured by a gauge manifold's high-side gauge during normal operation?

Evaporator saturation pressure
Condenser saturation pressure (Correct answer)
Suction line superheat
Liquid line subcooling

Correct answer: Condenser saturation pressure

The high-side gauge reads the discharge pressure, which corresponds to the condenser saturation pressure.

Question 99: Why use color-coded wiring?

For decoration
To confuse others
To mark insulation type
To maintain safety and standards (Correct answer)

Correct answer: To maintain safety and standards

To ensure correct and safe electrical connections.

Question 100: Which evaporator design is best suited for applications requiring precise humidity control, such as produce storage?

Plate-type evaporator
Large surface area, low TD evaporator (Correct answer)
Small surface area, high TD evaporator
Flooded shell-and-tube evaporator

Correct answer: Large surface area, low TD evaporator

A large surface area evaporator operating at a low temperature difference (TD) between air and refrigerant minimizes moisture removal from the stored product.

RSES Certifications (e.g., CM, CMS, RM, SM)

RSES offers various certifications for HVACR professionals, demonstrating expertise in specific areas like commercial refrigeration, domestic refrigeration, or HVACR electrical.

100

Questions

150 min

Time Limit

70%

To Pass

Checking for saved progress...

Exam Rules

You can skip questions and return to them later
Flag questions for review before submitting
No feedback shown until you submit the entire exam
Unanswered questions count as wrong — answer everything
10 pretest questions are mixed in and don't affect your score
Timer auto-submits when time runs out
Your progress is auto-saved every 30 seconds

These practice questions were written with AI tools. They are not real exam questions. Exam facts are checked against the official sources listed below. Not reviewed by a subject-matter expert. Editorial policy

Sources & references

Exam facts on this page (fees, format, dates, passing scores) are checked against these official sources; the date is our last check. Editorial policy

cdn.ymaws.com — Test delivery, retake fee, score release, time limit · verified Oct 2026
rses.org — Eligibility, fees, exam format, passing score, retake policy · verified Oct 2026