GM Metro/Sprint 1985-1993 Repair Guide



See Figure 1

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Fig. Fig. 1: Air conditioning system major components and refrigerant flow

The air conditioning compressor is driven by a drive belt from the engine crankshaft through an electromagnetic clutch. When voltage is applied to energize the clutch coil, a clutch plate and hub assembly are drawn rearward toward the pulley. As the compressor shaft turns, the compressor performs 2 functions. One is to compress the low pressure refrigerant vapor from the evaporator into a high pressure/temperature vapor. The other function is to pump refrigerant oil through the system to lubricate all components.

The condenser is mounted in front of the radiator and is comprised of small coils and cooling fins. When the high pressure/temperature vapor, from the compressor enters the condenser, heat is transferred from the refrigerant to the air passing through the front of the vehicle. The refrigerant is cooled and condensed into a liquid.

The receiver/drier is mounted on the fender and is connected to the condenser outlet and evaporator inlet. The receiver/drier is a temporary storage container for condensed liquid refrigerant, a filter which removes moisture and contaminants from the system incorporates a sight glass for checking the system's refrigerant charge.

The expansion valve regulates the flow of liquid refrigerant into the core of the evaporator. As the condensed liquid is released through the expansion valve, the pressure is decreased and the temperature drops causing the cooling effect.

The evaporator is housed in the evaporator case, located behind the right side of the instrument panel. During the air conditioning operation, ambient air is directed through the fins of the evaporator and into the vehicle's passenger compartment. As the air passes through the evaporator fins it is cooled.

R-12 refrigerant is a chlorofluorocarbon which, when released into the atmosphere, contributes to the depletion of the ozone layer in the upper atmosphere. Ozone filters out harmful radiation from the sun. DO NOT attempt to discharge the system by merely loosening a fitting. Discharging should only be performed using an approved recovery station. Consult the laws in your area before servicing the air conditioning system. In some states it is illegal to perform repairs involving refrigerant unless the work is done by a certified technician.