Understanding Automotive AC Systems

Which component in an automotive AC system is responsible for compressing the refrigerant and increasing its pressure?

• Condenser

• Compressor

• Evaporator

• Expansion valve

What is the primary function of the evaporator in an automotive AC system?

• To cool the refrigerant

• To absorb heat from the cabin air

• To compress the refrigerant

• To filter the refrigerant

Which of the following refrigerants is most commonly used in modern automotive AC systems?

• R-12

• R-134a

• Ammonia

• R-22

What property of a refrigerant allows it to absorb heat inside the vehicle and release it outside?

• High viscosity

• Ability to change phase at low pressure

• High density

• Low boiling point

Given a scenario where the AC system is not cooling effectively, which component would you check first for a possible blockage that could restrict refrigerant flow?

• Compressor

• Expansion valve

• Receiver-drier

• Blower motor

If a vehicle’s AC system is using R-134a refrigerant, what safety precaution should be taken when servicing the system?

• Use only water to clean the system

• Avoid mixing with R-12 refrigerant

• Store refrigerant in glass containers

• Operate the system with the windows open

A technician observes frost forming on the evaporator. What does this indicate about the operation of the AC system?

• The compressor is overcharged

• There is insufficient airflow over the evaporator

• The condenser is overheating

• The refrigerant is contaminated

Explain why the pressure of the refrigerant increases as it passes through the compressor in the AC system.

• The compressor adds heat to the refrigerant

• The compressor removes moisture from the refrigerant

• The compressor cools the refrigerant

A vehicle’s AC system is not cooling, and the technician finds that the high-pressure side is reading much higher than normal while the low-pressure side is lower than normal. What is the most likely cause?

• Overcharged refrigerant

• Blocked expansion valve or orifice tube

• Faulty compressor clutch

• Leaking evaporator

A customer complains that their AC system cools well at highway speeds but poorly at idle. Using your knowledge of AC system operation, what is the most probable explanation?

• The refrigerant is contaminated

• The condenser fan is not operating properly, reducing airflow at low speeds

• The compressor is overcharged

• The expansion valve is stuck open