A/C Pressure Sensor

The A/C pressure sensor converts A/C pressure into electrical signals to the ECM/PCM.

A/C System Pressure⁽¹⁾

Sensor Output Voltage (V out)

System Operation

Abnormally low pressure: Below 196 kPa (2.0 kgf/cm² , 28 psi)

Below 0.685 V

The ECM/PCM disengages the A/C compressor clutch.
The radiator and A/C condenser fans operate based on engine coolant temperature.

Normal operating pressure:

Above 196 kPa (2.0 kgf/cm² , 28 psi)
Below 1, 470 kPa (15.0 kgf/cm² , 213 psi)

0.686 V to 1.944 V

The ECM/PCM cycles the A/C compressor clutch based on cooling demand. The radiator and A/C condenser fans operate at low speed unless the engine coolant temperature exceeds 206°F (97 °C).

High operating pressure:

Above 1, 470 kPa (15.0 kgf/cm² , 213 psi)
Below 3, 138 kPa (32 kgf/cm² , 455 psi)

1.945 V to 4.575 V

The ECM/PCM cycles the A/C compressor clutch based on cooling demand. The radiator and A/C condenser fans operate at high speed.

Abnormally high pressure: More than 3, 138 kPa (32 kgf/cm² , 455 psi)

Above 4.575 V

The ECM/PCM disengages the A/C compressor clutch. The radiator and A/C condenser fans operate based on engine coolant temperature.

⁽¹⁾	The A/C system pressure can be monitored through the climate control sensor input display function (see RUN THE SENSOR INPUT DISPLAY MODE ).

The response of the A/C pressure sensor is shown in the graph in illustration below.

NOTE: When the refrigerant is below 196 kPa (2.0 kgf/cm² , 28 psi) or above 3, 138 kPa (32 kgf/cm² , 455 psi), the ECM/PCM turns the A/C compressor clutch relay off to protect the A/C compressor. When the refrigerant pressure is above 1, 470 kPa (15.0 kgf/cm² , 213 psi), the ECM/PCM switches the radiator and A/C condenser fans to high speed.

Fig 1: A/C Pressure Sensor Graph

Courtesy of AMERICAN HONDA MOTOR CO., INC.