All compressors are belt-driven from the engine crankshaft through the compressor clutch pulley. The compressor pulley rotates without driving the compressor shaft until on electromagnetic clutch coils energized. When voltage is applied to energize the clutch coil, the clutch plate and hub assembly are drawn toward the pulley. The magnetic force locks the clutch plate and pulley together as one unit to drive the compressor shaft.

The condenser assembly in front of the radiator consists of coils which carry the refrigerant and cooling fans that provide the rapid transfer of heat. The air passing through the condenser cools the high-pressure refrigerant vapor and causes it to condense into a liquid.

The expansion valve is located on the passenger compartment side of the dash panel. The expansion valve can fail in 3 different positions: open, closed, or restricted. An expansion valve that fails in the open position will result in a noisy A/C compressor or no cooling. The cause can be a broken spring, a broken ball, or excessive moisture in the A/C system. If the spring or the ball is found to be detective, replace the expansion valve. If excessive moisture is found in the A/C system, recycle the refrigerant. An expansion valve that fails in the closed position will result in low suction pressure and no cooling. This may be caused by a failed power down or excessive moisture in the A/C system. If the power dome on the expansion valve is found to be defective, replace the expansion valve. If excessive moisture is found in the A/C system, recycle the refrigerant.

A restricted expansion valve will result in low suction pressure and no cooling. This may be caused by debris in the refrigerant system. If debris is believed to be cause, recycle the refrigerant, replace the expansion valve, and replace the receiver/dryer.

The evaporator is a device which cools and dehumidifies the air before it enters the vehicle. High-pressure liquid refrigerant flows through the expansion tube, orifice, and becomes a low-pressure gas in the evaporator. The heat in the air passing through the evaporator core is transferred to the cooler surface of the core, which cools the air. As the process of heat transfer from the air to the evaporator core surface is taking place, any moisture, humidity, in the air condenses on the outside surface of the evaporator core and is drained off as water.

The sealed receiver-dryer assembly is connected to the evaporator outlet pipe. It acts as a refrigerant storing container, receiving liquid and some vapor and refrigerant oil from the evaporator.

At the bottom the receiver-dryer is the desiccant, which acts as a drying agent for the moisture that may have entered the system. The receiver-dryer is serviceable only as an assembly.

The dual cut switch controls compressor operation when the cycling refrigerant pressure is dropped or surged.

A semiconductor which resistance is noticeably changed as the change of temperature. When the refrigerant temperature of the evaporator drops to 0°C (32°F) and below, the evaporator cores get stuck with frost or ice, reducing the airflow, lowering the cooling capacity. The thermistor is a sensor which is used to prevent from frosting or icing.

The thermistor is installed on the evaporator.

The base heater system is designed to provide heating, ventilation, windshield defrosting, and side window defogging.

The heater and fan assembly blower regulates the airflow from the air inlet for further processing and distribution.

The heater core transfers the heat from the engine coolant to the inlet air.

The temperature door regulates the amount of the air that passes through the heater core. The temperature door also controls the temperature of the air by controlling the mix of the heated air and the ambient air.

The mode door regulates the flow and the distribution of the processed air to the heater ducts and to the defroster ducts.