Compressor HVAC: Description and Operation

A/C Compressor Switch-Out:





- The ICM will operate the A/C relay (2/22) if the A/C switch is operated while the blower is running, delivering power to the compressor electromagnetic clutch (8/3). Cycling of the compressor will then be controlled by the low-pressure switch (Pressostat) in the normal manner.
- The compressor is switched out in response to signals from the MFI module (4/45) under the following conditions, to prevent operation of the unit at maximum engine power or at high coolant temperature:
- Full acceleration: If the throttle is fully open, the ICM will keep the compressor switched out for a maximum of 15 seconds (and a minimum of 5 seconds).
- High temperature: Compressor operation will be inhibited if the coolant temperature is above approx. 125°C (257°F), to reduce the load on the engine and prevent further overheating.
- The ICM also inhibits compressor operation when the car is started, to ensure that the engine runs normally. The compressor is permitted to start only after approx. 5-15 seconds.