Exam 55: Heating and Air Conditioning Diagnosis and Service

The presence of oil on or around the compressor clutch normally indicates a bad ____________________

The ____________________ is a test instrument used to check the coil of a compressor clutch.

The blower motor on a vehicle does not run when the fan switch is in the low and medium position. It works properly when it is in the high position. Technician A says the problem is in the resistor block. Technician B says the problem is in the blower motor. Who is correct?

The owner of a car complains of a whistle or hiss only after the engine is shut down and only when the air-conditioning has been running. Technician A says there is a broken or leaking vacuum hose inside the dash. Technician B says this is a normal noise caused by the pressure of the refrigerant equalizing after the engine is turned off. Who is correct?

A manifold gauge set can be used during A/C system diagnosis.

An R-12 to R-134a conversion procedure is being discussed. Technician A says leak-test the system and conduct a performance test prior to removing the R-12. Technician B says leak-test the system and conduct a performance test after charging the system with R-134a. Who is correct?

A complaint concerning water on the front floor carpeting even in dry weather could be caused by _____

All new vehicles sold in the United States are required to have a cabin air filter or a slot where one can be installed.

R-12 to R-134a conversions are being discussed. Technician A says the original receiver/dryer or accumulator should not be replaced. Technician B says permanently install conversion fittings using a thread-locking chemical. Who is correct?

Electronic leak detectors are being discussed. Technician A checks for leaks with the engine off, the shop doors closed, and the overhead fans turned off. Technician B checks for leaks outdoors with the engine running. Who is correct?

How can you identify the type of refrigerant used in an A/C system?

In an R-12 to R-134a conversion, a high-pressure cutoff switch should be installed if the system does not have one.

Technician A says there should be a gradual change from hot to warm as you move your hand along the return bends of the condenser from the bottom to the top. Technician B says a restriction in the condenser will be evident by a sudden change in temperature. Who is correct?

Technician A says the sight glass is located in the suction line, between the accumulator and compressor. Technician B says the sight glass is located on the receiver/dryer. Who is correct?

Frost on the outside of the receiver/dryer, but not on the liquid line between the condenser and receiver/dryer indicates ______.

A manifold gauge set can be used during the evacuation of the A/C system.

During a performance test, both the low-side and high-side pressures are above normal. Technician A says the system is overcharged. T echnician B says there is insufficient airflow through the condenser. Who is correct?

Leaks in the evaporator core are generally caused by the corrosive combination of ____________________ and refrigerant, which combine to form hydrochloric acid.

The manifold gauge set has an inches-of-mercury (vacuum)scale on the _____ gauge.

When is a manifold gauge set used on an A/C system ?