AUTOMATIC AIR CONDITIONING SYSTEM: Compressor Control: Description

WARNING: This page is about a different car, the 2013 Infiniti M56 and 2013 Infiniti M37. However, it is still accessible from the selected car via links, so may be relevant.

When the compressor activation condition is satisfied while blower motor is activated, A/C auto amp. transmits A/C ON signal and blower fan ON signal to ECM via CAN communication.
ECM judges that the compressor can be activated depending on each sensors state (refrigerant pressure sensor signal, throttle position sensor signal, and others). And transmits air conditioner relay control signal to IPDM E/R via CAN communication.
IPDM E/R turns air conditioner relay ON and activates the compressor depending on request from ECM.