Compressor Controls

CIRCUIT OPERATION
The 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, and also allows the A/C load to be removed from the engine when needed.

Operation of the Compressor depends on the particular mode selected by the driver. When the A/C Mode Selector is in MAX, NORM, B/L, or DEF, battery voltage is applied through the HTR-A/C Fuse and Heater-A/C Compressor Control Relay to the remaining circuits.

When the mode selector is switched to MAX, NORM, B/L or DEF, voltage is applied to terminal C9, connector C1 through the A/C High Pressure Cut-Out Switch and the A/C Low Pressure Cut-Out Switch both of which are normally closed. The A/C Low Pressure Cut-Out Switch opens if the refrigerant charge is too low to operate the A/C compressor without possible damage to it. The A/C High Pressure Cut-Out Switch opens if refrigerant pressure is high enough that overheating of the engine may result.

The A/C Compressor Control Relay is operated by the ECM. When the ECM receives an A/C request signal, ground is provided at terminal F8, connector C3 energizing the relay.

The ECM will remove the ground at terminal F8, connector C3 to deenergize the relay when the air conditioning load should be removed from the engine, such as during wide open throttle.