Free Car Air Conditioning Repair Question and Answers — Questions and Answers
Question 1: Which of the following circumstances is most likely to result in a car overheating?
- Restricted heater core
- Thermostat stuck open
- Clogged radiator (Correct answer)
- Electric cooling fan runs all the time
Correct answer: Clogged radiator
A clogged radiator is one of the most common and critical causes of a car overheating. The radiator's primary function is to dissipate heat from the engine coolant. If its internal passages become blocked by debris, rust, or corrosion, the coolant flow is severely restricted, preventing effective heat exchange and causing the engine temperature to rise dangerously, leading to overheating.
Question 2: According to Technician A, when the condenser airflow is restricted, both the high and low lines are under high pressure. When the pressure is low on both the high and low sides, according to technician B, this is a sign of low refrigerant. Who is correct?
- Technician B only
- Technician A only
- Neither Technician A nor B
- Both Technician A and B (Correct answer)
Correct answer: Both Technician A and B
Technician A is correct because restricted condenser airflow prevents the system from dissipating heat effectively, causing refrigerant to remain in a high-pressure, high-temperature state throughout, leading to high readings on both gauges. Technician B is also correct; a low refrigerant charge means there isn't enough fluid to build proper pressure, resulting in low pressure readings on both the high and low sides of the system. Both scenarios describe distinct, valid diagnostic indicators in AC systems.
Question 3: The following facts about an air conditioning performance test are all true, EXCEPT for
- Obstructions of the cabin air filter may cause insufficient air circulation.
- Road debris can clog the condenser fins reducing system performance
- To avoid outside odor, operate AC System in RECIRC rather than FRESH mode (Correct answer)
- Passenger-side floor being wet is one symptom of a clogged evaporator drain line
Correct answer: To avoid outside odor, operate AC System in RECIRC rather than FRESH mode
The question asks for the statement that is NOT true. Operating the AC system in RECIRC (recirculation) mode *does* help avoid outside odors by closing the fresh air intake and recirculating cabin air. Therefore, this statement is actually true, making it the incorrect answer for an 'EXCEPT' question. The other options correctly describe common AC system issues or symptoms.
Question 4: The engine may run excessively cold, according to Technician A, if the thermostat is broken. The thermostat can generate a pinging or pounding noise if it is jammed closed, according to technician B. Who is correct?
- Technician B only
- Technician A only
- Neither Technician A nor B
- Both Technician A and B (Correct answer)
Correct answer: Both Technician A and B
Technician A is correct because a thermostat stuck open will allow coolant to continuously flow through the radiator, preventing the engine from reaching its optimal operating temperature and causing it to run excessively cold. Technician B is also correct; a thermostat jammed closed will restrict coolant flow, leading to severe engine overheating and potential pinging or pounding noises from boiling coolant and pressure buildup. Both technicians accurately describe potential thermostat malfunctions and their symptoms.
Question 5: The technician observes that the compressor output is warm when testing the performance of the air conditioner. This is a typical condition, according to technician A. The air conditioning system, according to technician B, is overcharged. Who is correct?
- Technician B only
- Technician A only (Correct answer)
- Neither Technician A nor B
- Both Technician A and B
Correct answer: Technician A only
Technician A is correct because the compressor's function is to compress low-pressure, low-temperature gaseous refrigerant into high-pressure, high-temperature gas. This compression process inherently generates heat, making the compressor output naturally warm or hot during normal operation. Therefore, a warm compressor output is a typical condition and not indicative of an overcharged system.
Question 6: If the condenser fan wasn't working, what high-side and low-side pressure gauge readings might a technician discover?
- Both high-side high and low-side are high (Correct answer)
- High-side high and low-side low
- High-side low and low-side high
- Both high-side high and low-side are low
Correct answer: Both high-side high and low-side are high
If the condenser fan is not working, the condenser cannot effectively dissipate the heat from the high-pressure refrigerant. This causes the refrigerant to remain in a high-pressure, high-temperature state throughout the system, leading to abnormally high pressure readings on both the high and low sides of the system. The system struggles to cool because the heat is not being rejected to the ambient air.
Question 7: Which of the following issues will result in the various gauge readings depicted in the illustration?
- Low refrigerant
- Expansion valve stuck closed
- Restricted condenser airflow
- Refrigerant overcharge (Correct answer)
Correct answer: Refrigerant overcharge
A refrigerant overcharge means there is too much refrigerant in the system. This excess volume causes abnormally high pressures on both the high and low sides, as the compressor tries to move more refrigerant than the system is designed for. The high-side pressure will be significantly elevated, and the low-side pressure will also be higher than normal, indicating the system is struggling to properly cycle the refrigerant.
Free Car Air Conditioning Repair Question and Answers
Which of the following circumstances is most likely to result in a car overheating?