With 4L60E Automatic Transmission

A/C Request Signal Circuit (PCM):

Circuit and Test Description:
Turning "ON" the air conditioning supplies CKT 59 battery voltage to the A/C compressor clutch and to terminal "E12 of the control module connector to increase and maintain idle speed.

The control module does not control the A/C compressor clutch, therefore, if A/C does not function, refer to the A/C section.

If A/C is operating properly and idle speed dips too low when the A/C compressor turns "ON" or flares too high when the A/C compressor turns "OFF", check for an open CKT 59 to the control module. If circuits are OK, it is a faulty control module connector terminal "E12" or PCM.