Aurora V8-4.0L VIN C (1996)
A/C Signal: Description and Operation
Compressor Control Signal
DESCRIPTION
In order to improve engine operation, the A/C compressor operation is controlled by the PCM.
OPERATION
This system consists of a HVAC control assembly, separate A/C refrigerant high and low pressure switches, separate A/C high and low temperature
sensors, a control relay, the compressor clutch and the PCM. When the HVAC control assembly is placed in the A/C mode, a request signal is sent to
the PCM. The PCM will then energize the A/C clutch relay, unless abnormally high or low A/C pressure is detected by the A/C refrigerant pressure
switches. The PCM also monitors the A/C low temperature sensors to cycle the A/C clutch ON and OFF. If the PCM detects an A/C evaporator
temperature less than 2° C (36° F), the A/C clutch will be prohibited from being enabled. The PCM will also energize the cooling fans ON when A/C
is requested. The A/C control relay is controlled by the PCM so that the PCM can increase idle speed before turning ON the clutch or disable the
clutch when high engine coolant temperature is detected or high engine RPM is detected.
