Air Conditioning Repair Installation and Service Procedures 3 — Questions and Answers
Question 1: What is the correct sequence for recovering refrigerant from a system before a major repair?
- Recover, then evacuate, then repair
- Repair, then recover remaining refrigerant
- Recover refrigerant, then repair, then recharge (Correct answer)
- Evacuate with a vacuum pump first, then recover
Correct answer: Recover refrigerant, then repair, then recharge
EPA Section 608 requires recovering refrigerant before opening the system; after repairs, the system is then evacuated and recharged.
Question 2: A condensate drain line is routed through an unconditioned attic. What additional measure is required by most building codes?
- Insulate the drain line to prevent sweating and dripping (Correct answer)
- Install a condensate pump at the air handler
- Use schedule 80 PVC instead of schedule 40
- Increase the drain line diameter to 1 inch
Correct answer: Insulate the drain line to prevent sweating and dripping
Uninsulated condensate drain lines in hot unconditioned spaces can sweat and drip, causing water damage and mold — insulation prevents this.
Question 3: When setting up a manifold gauge set on an R-410A system, the technician should use hoses rated for at least:
- 300 psi working pressure
- 500 psi working pressure
- 800 psi working pressure (Correct answer)
- 1,000 psi working pressure
Correct answer: 800 psi working pressure
R-410A operates at pressures roughly 60–70% higher than R-22; hoses rated at 800 psi working pressure (4,000 psi burst) are the minimum standard.
Question 4: 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?
- Improved comfort due to higher airflow
- Higher static pressure, reduced airflow, poor efficiency and comfort (Correct answer)
- Reduced refrigerant charge requirement
- Faster system response time
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 5: What is the purpose of an access port Schrader valve core removal tool during service?
- To replace a damaged Schrader valve while the system is pressurized
- To allow full-flow refrigerant access without restricting flow through the valve core (Correct answer)
- To test for valve leaks
- To add dye to the system
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 6: After replacing a compressor, what maintenance item is most critical before recharging the system?
- Replace the air filter
- Change the thermostat batteries
- Replace the filter drier (Correct answer)
- Clean the condenser coil
Correct answer: Replace the filter drier
Compressor burnout releases acids and contaminants into the refrigerant circuit; a new filter drier removes these contaminants to protect the replacement compressor.
Question 7: When installing a condensing unit on a rooftop, which mounting concern is most important for long-term reliability?
- The unit must face north to avoid sun exposure
- The unit must be level to ensure proper compressor oil lubrication (Correct answer)
- The disconnect must be within 5 feet of the unit
- The unit must be at least 10 feet from the roof edge
Correct answer: The unit must be level to ensure proper compressor oil lubrication
A level condensing unit ensures the compressor crankcase maintains proper oil level for lubrication; an unlevel unit can cause oil to pool away from the oil pickup.
Air Conditioning Repair Installation and Service Procedures 3
What is the correct sequence for recovering refrigerant from a system before a major repair?