Compressor HVAC: Description and Operation

V-5 Compressor - 2.3L (VIN D & A):

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

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

For vehicles equipped with the L4 VIN D or L4 VIN A engine, operation is similar to that of the L4 VIN U engine except the L4 VIN D and L4 VIN A do not use an A/C High Pressure Cut-Out Switch or an A/C Low Pressure Cut-Out Switch. Instead they use an A/C Compressor Refrigerant Pressure Sensor.

The A/C Compressor Refrigerant Pressure Sensor sends a voltage to the ECM at terminal F14 of connector C3 which varies between 0.50 volts, 1137 kPa (165 psi) and 4.50 volts, 2750 kPa (399 psi). The ECM controls engine idle speed to compensate for the greater engine refrigerant load created by high pressure. If the voltage is out of this range for more than 5 seconds, code 66 is set, signaling the ECM to de-energize the A/C Compressor Control Relay.