Air Conditioning Repair Installation and Service Procedures 2 — Questions and Answers
Question 1: What is the minimum required clearance between a condensing unit and a wall or fence on the service side?
- 12 inches
- 18 inches
- 24 inches (Correct answer)
- 36 inches
Correct answer: 24 inches
ACCA and most manufacturer specifications require at least 24 inches of clearance on the service side of a condensing unit for proper airflow and technician access.
Question 2: When installing a new evaporator coil, what should be done to the existing refrigerant metering device?
- Reuse it if it appears undamaged
- Replace it with the OEM-matched device supplied with the coil (Correct answer)
- Upgrade to the next larger size
- Remove it entirely and use only the coil's distributor
Correct answer: Replace it with the OEM-matched device supplied with the coil
The metering device must be matched to the new coil's specifications; the OEM-supplied device ensures proper refrigerant distribution and system efficiency.
Question 3: 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
- Vibration isolation hangers (Correct answer)
- Saddle clamps
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 4: What is the purpose of trapping the suction line at the base of a vertical rise when the evaporator is located above the condensing unit?
- To increase suction pressure
- To prevent oil from draining back and flooding the compressor during off cycles (Correct answer)
- To reduce refrigerant velocity
- To allow for thermal expansion
Correct answer: To prevent oil from draining back and flooding the compressor during off cycles
An oil trap at the base of a suction line riser ensures oil circulates back to the compressor and does not accumulate in the low point of the line.
Question 5: A technician is installing a split system where the line set run is 75 feet — 25 feet longer than the manufacturer's standard. What adjustment is typically required?
- Increase the thermostat setpoint by 2°F
- Add refrigerant charge per the manufacturer's extended line set table (Correct answer)
- Increase blower speed by one tap
- Install a second TXV in series
Correct answer: Add refrigerant charge per the manufacturer's extended line set table
Manufacturers publish refrigerant add-per-foot tables for line sets longer than the tested standard length to compensate for the additional volume.
Question 6: When brazing copper refrigerant lines, nitrogen should be flowing through the lines at what approximate pressure?
- 0 psig (off)
- 2–5 psig (Correct answer)
- 15–20 psig
- 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 7: During a new system startup, the technician measures superheat at 5°F on a fixed-orifice system. What does this indicate?
- The system is properly charged
- The system is overcharged (Correct answer)
- The system is undercharged
- The compressor is running at high efficiency
Correct answer: The system is overcharged
Very low superheat (below the target of ~10°F on most fixed-orifice systems) indicates an overcharge, which risks liquid refrigerant entering the compressor.
