Symptom Diagnostic Charts

Wiring Diagram For Chart C-10A - A/C "On" Signal Diagnosis:

CHART C-10A - A/C "ON" SIGNAL DIAGNOSIS


Circuit And Test Description:

Turning on the air conditioning supplies CKT 59 battery voltage to the A/C compressor clutch and to terminal "B8" of the ECM connector to increase idle air rate and maintain idle speed.

The ECM does not control the A/C compressor clutch, therefore, if A/C does not function, refer to the A/C section of the service manual for diagnosis of the system.

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 ECM. If circuits are OK, it is a faulty ECM connector terminal "B8" or ECM.