A/C Pressure Sensor

Used by the fuel injection ECU:

OPERATION
When the AC compressor is in operation, an electrical signal is sent from the pressure sensor (located on the receiver/dryer at passenger side fire-wall) to the ECU.

When the A/C system pressure is low, the pressure sensor will come on (A/C compressor turns on) and send a signal to the ECU. If the pressure is sufficient for the A/C system to operate without the compressor, the pressure sensor will stay off and no signal is sent to the ECU.