C 2500 Truck 2WD V8-5.7L VIN R (1997)
A/C Signal: Description and Operation
The A/C request circuit signals the VCM when an A/C mode is selected at the A/C control head. The VCM uses this information to 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 VCM, the A/C compressor will be
inoperative. Refer to A/C Clutch Circuit Diagnosis for A/C wiring diagrams and diagnosis of A/C electrical system.