A/C on Signal

Wiring Diagram (A/C Clutch Control Circuit):

NOTE: Because different models and engine applications vary in wire colors, circuit numbers, and pin numbers, the above image is a typical example. Refer to COMPUTERS AND CONTROL SYSTEMS/SCHEMATIC AND ROUTING DIAGRAMS for specific schematic applications.

PURPOSE
This signal indicates that the A/C control switch is turned "ON" and the pressure switch is closed.

OPERATION
The ECM/PCM uses this signal to adjust the idle speed, and on some models engages the A/C compressor clutch. If this signal is not available to the ECM/PCM, the engine idle may be rough when the A/C compressor cycles. In some cases the A/C compressor will be inoperative.