Air conditioning (A/C) compressor

Fig 1: Identifying Air Conditioning (A/C) Pressure Sensor

Courtesy of VOLVO CARS OF NORTH AMERICA.

The air conditioning (A/C) pressure sensor detects the pressure in the high-pressure side of the air conditioning (A/C) system. This is so the engine control module (ECM) can control:

• start-up of the engine cooling fan (FC) step 2
• start-up of the engine cooling fan (FC) step 3
• stopping the compressor if the pressure in the air conditioning (A/C) is too high
• constant idle speed compensation for the air conditioning (A/C) compressor load.

The sensor is linear. It is grounded in the control module and supplied with a 5 Volt current from the control module. A linear signal (between 0-5 V depending on the pressure in the air conditioning (A/C)) is transmitted to the control module. Low pressure produces low voltage, high pressure produces high voltage.

The engine control module (ECM) can diagnose the air conditioning (A/C) pressure sensor. The sensor value can be read off using VIDA.

The air conditioning (A/C) pressure sensor is positioned on the high pressure delivery line for the air conditioning (A/C) system.