NAPA Heating and Air Conditioning 5 — Questions and Answers
Question 1: Under the Clean Air Act, what is required for a technician to service motor vehicle A/C systems for pay?
- ASE A6 certification
- EPA Section 609 certification (Correct answer)
- EPA Section 608 Universal certification
- A state contractor license
Correct answer: EPA Section 609 certification
Section 609 certification is required to service MVAC systems and buy small cans of refrigerant for professional use.
Question 2: What safety characteristic of R-1234yf requires special service equipment and procedures?
- It is highly toxic
- It is mildly flammable (A2L classification) (Correct answer)
- It is not compatible with any oil
- It operates at much higher pressures than R-134a
Correct answer: It is mildly flammable (A2L classification)
R-1234yf is classified A2L, mildly flammable, so equipment meeting SAE J2843 and unique fittings are required.
Question 3: On a hybrid vehicle with a high-voltage electric A/C compressor, why must the correct specified oil (often POE) be used?
- To improve fuel economy
- Wrong oil can reduce electrical insulation and create a shock or failure risk (Correct answer)
- PAG oil causes refrigerant to leak
- Electric compressors require no oil
Correct answer: Wrong oil can reduce electrical insulation and create a shock or failure risk
The oil contacts the motor windings, so conductive or incorrect oil can compromise high-voltage insulation.
Question 4: Why is a deep vacuum pulled on an A/C system after it has been opened for repair?
- To check the compressor clutch
- To remove air and boil off moisture at low pressure (Correct answer)
- To clean oil from the lines
- To test the blower motor
Correct answer: To remove air and boil off moisture at low pressure
Lowering pressure lowers water's boiling point so moisture vaporizes and is removed along with air.
Question 5: Which component should typically be replaced whenever an A/C system is opened for major repair or has been left open to the atmosphere?
- Receiver-drier or accumulator (Correct answer)
- Condenser fan motor
- Heater core
- Blend door actuator
Correct answer: Receiver-drier or accumulator
The desiccant in the drier or accumulator saturates with moisture and must be replaced to protect the system.
Question 6: On a TXV-type A/C system, where is the receiver-drier located?
- Low side between the evaporator and compressor
- High side between the condenser and expansion valve (Correct answer)
- Inside the evaporator case
- Between the compressor and condenser
Correct answer: High side between the condenser and expansion valve
The receiver-drier stores liquid refrigerant on the high side ahead of the expansion valve.
Question 7: A customer complains of a musty odor when the A/C is first turned on. What is the most appropriate repair?
- Recharge the refrigerant
- Clean the evaporator with an approved treatment and replace the cabin air filter (Correct answer)
- Replace the heater core
- Flush the cooling system
Correct answer: Clean the evaporator with an approved treatment and replace the cabin air filter
Mold and bacteria on the damp evaporator cause the odor and are treated with evaporator cleaner and a fresh filter.
