ASE ASE Heating & Air Conditioning 1 — Questions and Answers
Question 1: Which refrigerant is currently mandated for use in most new US passenger vehicle air conditioning systems?
- R-12
- R-134a
- R-1234yf (Correct answer)
- R-22
Correct answer: R-1234yf
R-1234yf has replaced R-134a as the mandated refrigerant in most new US vehicles due to its lower global warming potential.
Question 2: What component in an automotive A/C system separates liquid refrigerant from vapor before it enters the compressor?
- Condenser
- Accumulator (Correct answer)
- Evaporator
- Expansion valve
Correct answer: Accumulator
The accumulator, located on the low side between the evaporator and compressor, stores excess liquid refrigerant to prevent compressor damage.
Question 3: A technician finds a vehicle's A/C blows cold air at highway speeds but warm at idle. What is the MOST likely cause?
- Low refrigerant charge
- Faulty condenser fan (Correct answer)
- Clogged expansion valve
- Worn compressor clutch
Correct answer: Faulty condenser fan
A faulty condenser fan reduces airflow at idle when ram air is absent, preventing proper heat dissipation and causing warm A/C output.
Question 4: What does superheat measurement indicate during an A/C system diagnosis?
- Compressor efficiency
- Amount of refrigerant vapor above its boiling point at the evaporator outlet (Correct answer)
- Condenser outlet temperature
- Receiver-drier saturation level
Correct answer: Amount of refrigerant vapor above its boiling point at the evaporator outlet
Superheat is the temperature rise of refrigerant vapor above its saturation point at the evaporator outlet, used to verify proper evaporator flooding.
Question 5: When recovering refrigerant from an A/C system, a technician must use EPA-certified equipment per which regulation?
- EPA Section 608 (Correct answer)
- CAA Title II
- OSHA 29 CFR 1910
- DOT 49 CFR 173
Correct answer: EPA Section 608
EPA Section 608 of the Clean Air Act requires certified recovery equipment to prevent venting of refrigerants to the atmosphere.
Question 6: Which tool is used to measure the high-side and low-side pressures of an A/C system simultaneously?
- Vacuum pump
- Manifold gauge set (Correct answer)
- Leak detector
- Thermistor probe
Correct answer: Manifold gauge set
A manifold gauge set connects to both service ports and displays high-side and low-side pressures simultaneously for system diagnosis.
ASE ASE Heating & Air Conditioning 1
Which refrigerant is currently mandated for use in most new US passenger vehicle air conditioning systems?