Throttle Full Open Switch: Description and Operation

PURPOSE
The Wide Open Throttle Air Conditioning Cut-off (WAC) output is used by the PCM to disengage the A/C clutch when compressor operation is not desirable.

OPERATION
When A/C is requested to the Powertrain Control Module (PCM) through the A/C Cycling Switch (ACCS) input, the PCM verifies that A/C clutch operation is desirable (example: engine not cranking or overheated, not at WOT, etc.). If A/C clutch operation is desirable, the PCM will adjust idle speed as necessary and "unground" the WAC output, which signals to the Constant Control Relay Module (CCRM) that the A/C clutch may be activated. The CCRM then supplies voltage to the Power-To-A/C Clutch circuit, activating the A/C clutch. If the PCM determines operation is not desirable the WAC output is turned on (grounded) and the CCRM turns off the A/C clutch. Under normal conditions with the A/C Off the PCM grounds the WAC output. The solid state A/C WAC Relay functions as a normally closed relay.