A/C Pressure Sensor

A/C Clutch Control Circuit "L" Carline:

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
The A/C pressure sensor provides a signal to the ECM which indicates varying high side refrigerant pressure between approximately 0.0 psi to 450 psi. The ECM uses this input to determine A/C compressor load on the engine to help control idle speed with the Idle Air Control (IAC) Valve.

OPERATION
The A/C pressure sensor electrical circuit consist of a 5.0 volt reference line, a ground, and a signal wire to the ECM. The signal is a voltage that varies from approximately 0.1 volts at 0.0 psi to 4.9 volts at 450 psi or more. A problem with the A/C pressure circuits or sensor should set a Code 66 and will make the A/C compressor inoperative.

LOCATION
High side pressure line between the compressor and the condenser.