Compressor HVAC: Description and Operation

CIRCUIT OPERATION
The A/C Compressor for the Air Conditioning System is belt-driven by the engine through the A/C Compressor Clutch. The clutch allows the compressor to be disengaged when air conditioning is not required, or to remove the air conditioning load from the engine when necessary.

Operation of the compressor depends on the particular A/C mode selected by the driver. When the A/C Mode Selector is in MAX, NORM, HI-LEVEL or DEF, battery voltage is applied through Fuse 8 and the Heater and A/C Control Assembly Selector to the A/C Compressor Control Relay

DESCRIPTION
The voltage path from the Heater and A/C Control Assembly is through the A/C Low Pressure Switch to the contacts of the A/C Compressor Relay. Voltage is also applied to terminal C1/C9 of the Electronic Control Module (ECM) through the normally closed contacts of the A/C High Pressure Switch. When the ECM receives the voltage input at terminal C1/C9, it will ground terminal C3/F1 to energize the A/C Compressor Control Relay. The A/C Low Pressure Switch and A/C High Pressure Switch operate as described for the L4 VIN G engine.

When the A/C Compressor Control Relay is energized, it applies voltage through its contacts to the A/C Compressor Clutch. The ECM will remove the ground at terminal C3/F1 to deenergize the A/C Compressor Control Relay when the A/C load should be removed from the engine.