A/C Pressure Sensor

A/C Compressor Clutch Wiring Diagram:

Purpose:
The ECM monitors A/C refrigerant pressure and A/C evaporator temperature to determine if the A/C system has adequate refrigerant (R134a) charge. The ECM will disable the A/C clutch whenever A/C refrigerant charge drops below a predetermined value, to reduce the chance of compressor damage.

Operation:

A/C Pressure Sensor
A 5 volt reference is supplied to the sensor and returned to the ECM on the signal line. As A/C pressure increases or decreases, the resistance of the sensor changes and varies the amount of signal returning to the ECM.

A/C Evaporator Temperature Sensor
A 5 volt reference is supplied to the sensor and returned to the ECM on the signal line. As evaporator temperature increases or decreases, the resistance of the sensor changes and varies the amount of signal returning to the ECM.

Location:
The A/C pressure sensor is located above the right hand shock tower, forward of the A/C compressor.

The A/C evaporator temperature sensor is mounted in the evaporator core.