A/C Signal: Description and Operation

A/C Clutch Cycling Pressure Switch:

PURPOSE
used as an input to determine electronic pressure control when the air conditioning clutch is engaged to compensate for the additional load on the engine.

OPERATION
The Air Conditioning Clutch is an electromagnetic clutch that is energized when the clutch cycling A/C pressure cut-off switch closes. The A/C pressure cut-off switch is located on the suction accumulator-drier. The closing of the A/C pressure cut-off switch completes the circuit to the clutch and draws it into engagement with the compressor driveshaft, and also sends a 12v signal to the Powertrain Control Module (PCM) to determine output for transmission electronic pressure control.

SYMPTOMS
^ Failed on - electronic pressure control slightly low with A/C off
^ Failed off - electronic pressure control slightly high with A/C on

DAGNOSTIC TROUBLE CODES
-67(two digit)
-539 (three digit)