A/C Operation Description at ECM: Notes
WARNING: This page is about a different car, the 2011 Suzuki SX4. However, it is still accessible from the selected car via links, so may be relevant.
ECM controls the A/C compressor relay and condenser cooling fan relay according to signals from HVAC control unit, A/C refrigerant pressure sensor, ECT sensor and evaporator temperature sensor. The A/C switch ON signal from HVAC control unit is transmitted to ECM through BCM by CAN communication system. For more information about CAN communication system, refer to CAN COMMUNICATION SYSTEM DESCRIPTION .
ECM turns ON the A/C compressor relay when the vehicle state satisfy conditions described below.
- A/C switch ON signal is input from HVAC control unit
- A/C refrigerant pressure is within specified range
- Evaporator temperature is within specified range
- Engine speed is within specified range
- Engine coolant temperature is lower than specified value
- Throttle opening is lower than specified value
- Vehicle is not in either state of starting or quick acceleration
- ECT sensor malfunction is not detected
- A/C refrigerant pressure sensor malfunction is not detected