Exam 54: Heating and Air Conditioning

The high pressure cutout switch disengages the compressor clutch when high-side pressure reaches _____ psi.

What is the purpose of the ambient temperature switch?

Most modern heater cores are made of ____________________ cores with plastic tanks.

In most vehicles, the air-conditioning compressor will turn off when the defroster is selected by the driver and the ambient temperature is more than 35°F.

All materials or substances, as cold as ______, have heat in them.

All manufacturers recommend reverse flushing their heater cores.

Technician A says the thermostatic expansion valve and the fixed orifice tube perform the same function. Technician B says heat from the evaporator core surface is lost to the boiling and vaporizing refrigerant. Who is correct?

Technician A says R-12 is a chlorofluorocarbon (CFC)that damages Earth's ozone layer. Technician B says R-134a is a hydrofluorocarbon (HFC)that causes even greater damage. Who is correct?

Which statement is false?

Technician A says suction lines connect the accumulator to the compressor. Technician B says discharge lines connect the compressor to the condenser. Who is correct?

Most vehicles have a cabin filtration system that cleans the air before it enters the passenger compartment.

The heater ____________________ is generally designed and constructed much like a miniature radiator.

Technician A says in most cases, problems with the heating system are problems with the engine's cooling system. Technician B says a restricted heater return hose can cause excess heat in the passenger compartment. Who is correct?

Many technicians cut old heater hoses at the pipe connections and replace them.

On which of the following laws of nature is the air-conditioning system based?

The change from a vapor to a liquid is called ____________________.

Technician A says when the pressure applied to a liquid is increased, the boiling point decreases. Technician B says when the pressure on a liquid is suddenly released, heat energy is absorbed into the liquid. Who is correct?

The boiling point of a liquid increases as ______.

Technician A says the magnetic clutch is usually pressure controlled, cycling the compressor on and off to regulate system temperature or pressure. Technician B says the clutch operates continually when the system is turned on. Who is correct?

Air-conditioning systems that use an accumulator come equipped with a sight glass.