A/C Request, Input

A/C Request Signal

Description
The A/C request circuit signals the PCM when an A/C mode is selected at the A/C control head. The PCM uses this information enable the A/C compressor clutch and to adjust the idle speed before turning "ON" the A/C clutch. If this signal is not available to the PCM, the A/C compressor will be inoperative.

Operation
The PCM will energize the A/C clutch whenever the engine is running less than 4100 RPM and A/C has been requested, unless any of the following conditions are met:

^ Wide Open Throttle (WOT).

^ A/C head pressure greater than 429 psi or less than 0 psi (as determined by the A/C refrigerant pressure sensor).

^ Ignition voltage less than 10 volts.

^ Engine speed greater than 5550 RPM for 180 seconds

^ ECT greater than 125°C (257°F).