Relays and Switches

Compressor Control Relay

The compressor clutch coil is energized through the compressor control relay. This relay is activated by the PCM in A/C modes. The PCM provides cut-off of the relay under certain operating conditions such as wide open throttle.

A/C Refrigerant Pressure Sensor

An electronic A/C pressure sensor is mounted to the line (between the condenser and the evaporator). The output to the PCM is variable and is dependent upon pressure inside the line. A higher pressure results in a higher voltage out. The PCM constantly monitors A/C system pressure to:

1. Disengage the A/C clutch if the pressures are too high, 2700 kPa (440 psi.).

2. Disengage the A/C clutch if pressures are too low, below 285 kPa (38 psi.).

3. Boost idle air control to compensate for A/C load at idle.

4. Control cooling fan operation. The pressure sensor is not repairable, if it fails, it must be replaced.