Air Conditioning: Notes

The air conditioning system components are:

• A/C compressor (19703)
• A/C condenser core (19712)
• A/C evaporator core (part of 19850 assembly)
• receiver/drier (19959)
• connecting refrigerant lines
• thermostatic expansion valve assembly(19849)
• A/C thermostatic switch
• Refrigerant containment switch (19D594)
• A/C compressor pressure relief valve (19D644)
• low charge protection switch (19E561)

  The refrigerant system incorporates an A/C compressor controlled by the powertrain control module (PCM) through an A/C clutch relay.

• The A/C compressor clutch will only be engaged by the PCM if all of the following conditions are met:
• The climate control assembly is set to a mode which provides an A/C request to the PCM.
• The A/C thermostatic switch is reading an acceptable temperature (4°C/39.5°F).
• The refrigerant containment switch is not open due to excessive pressure in the high side of the refrigerant system.
• The low charge protection switch is not open due to insufficient low side refrigerant system pressure.
• The A/C compressor relay is switched to the closed position by the PCM.
• The engine coolant temperature is not excessively high.
• The PCM has not detected a wide open throttle (WOT) condition.

An A/C compressor pressure relief valve is installed in the compressor manifold and tube assembly (19D734) to protect the refrigerant system against excessively high refrigerant pressures.

Refrigerant flow into the evaporator core is metered by a thermostatic expansion valve.