Magnet Clutch Control
WARNING: This page is about a different car, the 2008 Nissan Quest. However, it is still accessible from the selected car via links, so may be relevant.
When the A/C switch is pressed, or the defroster mode switch is pressed, the front air control outputs a compressor ON signal to BCM.
The BCM then sends a compressor ON signal to ECM and front air control, via CAN communication line.
ECM judges whether compressor can be turned ON, based on each sensor status (refrigerant pressure sensor signal, throttle angle sensor, etc.). If it judges compressor can be turned ON, it sends compressor ON signal to IPDM E/R, via CAN communication line.
Upon receipt of compressor ON signal from ECM, IPDM E/R turns air conditioner relay ON to operate compressor.