Car Air Conditioning Repair Flashcards
7 cards from real Air Conditioning Repair practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Car Air Conditioning Repair flashcards as text
Which refrigerant replaced R-12 in most automotive AC systems manufactured after 1994?
Answer: R-134a
R-134a became the standard automotive refrigerant after the EPA phased out ozone-depleting R-12 under the Clean Air Act, though newer vehicles use R-1234yf.
A customer complains of a musty odor from the AC vents but normal cooling. What is the most likely cause?
Answer: Mold or bacteria growth on the evaporator coil
Moisture and organic debris on the evaporator surface create an ideal environment for mold and bacteria, producing a musty smell that enters the cabin through the vents.
What does TXV stand for in an automotive AC system, and what is its function?
Answer: Thermal Expansion Valve — meters refrigerant flow into the evaporator
The Thermal Expansion Valve (TXV) regulates the amount of refrigerant entering the evaporator based on evaporator outlet temperature, optimizing efficiency.
Both high-side and low-side pressures are abnormally low on a running AC system. What does this most likely indicate?
Answer: System is undercharged (low refrigerant)
When both pressures are uniformly low, the refrigerant charge is insufficient to maintain normal operating pressures on either side of the system.
When replacing an AC compressor, why must a specific amount of oil be added to the new unit?
Answer: To compensate for oil retained in old system components
Old system components (condenser, evaporator, lines) retain a portion of compressor oil, so the replacement compressor must be pre-filled to match total system oil capacity.
A car AC condenser fan runs only when the AC is on. The engine is overheating in traffic. What is the likely fault?
Answer: Condenser fan relay or control wiring not triggering the fan for engine cooling
The condenser fan should activate both for AC operation and independently when coolant temperature reaches a threshold; a relay or wiring fault can disable the cooling-mode trigger.
What safety precaution must be taken when handling R-134a refrigerant in liquid form?
Answer: Wear safety goggles and insulated gloves to prevent frostbite
Liquid R-134a evaporates rapidly on contact with skin or eyes, causing severe frostbite and injury; PPE including goggles and thermal-insulating gloves is required.