A/C Signal: Description and Operation

A/C Pressure Sensor:

PURPOSE
The A/C pressure sensor supplies the ECM with a linear signal regarding pressure in the A/C high-pressure circuit. The ECM uses this signal to control:
^ Starting of the engine cooling fan (high and low speed).
^ Switch-out of the A/C compressor if system pressure becomes excessive.

LOCATION
Installed in the A/C high-pressure circuit.

OPERATION
The sensor receives a 5 VDC signal from the ECM. The sensor returns an equal or lower voltage signal to the ECM (indicating system pressure). Low pressure returns a low voltage signal, high pressure returns a high voltage signal.