K 2500 Truck 4WD V8-350 5.7L VIN K TBI (1995)
A/C Signal: Testing and Inspection
Engine Control Module - ECM
A/C Circuit
CIRCUIT AND CHART 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 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.
