Faulty A/C Compressor
A/C Compressor harness is open or shorted
A/C Compressor circuit poor electrical connection
Engine Light ON (or Service Engine Soon Warning Light)
The AC compressor function is to provide refrigerant flow in the AC refrigerant loop to help cool down the cabin, help dehumidify the air in a defrost mode and help maintain the battery temperature. Rather than a more typical pulley, the A/C compressor uses a 3-phase alternating current, high voltage electric motor to operate. It has an on-board inverter that takes High Voltage direct current from the vehicle’s High voltage battery and inverts it to alternating current for the motor. The AC compressor shall be activated when any of the three following events occur:
– The customer pushes the AC button
– The HVAC control, in AUTO mode, requests the electric AC compressor on to help in cooling the cabin or removing moisture in the defrost mode
– The High Voltage Battery Thermal System requests the AC compressor on to help maintain the battery temperature
The Hybrid/EV Powertrain Control Module 2 uses values from the A/C refrigerant pressure transducers, A/C refrigerant thermistor, duct temperature sensors, ambient air temperature sensor, passenger compartment temperature sensor, evaporator temperature sensor, battery cell temperature sensors, battery coolant temperature sensors and battery coolant pumps to determine the speed at which the compressor will operate. This message is sent from the Hybrid/EV Powertrain Control Module 2 to the A/C compressor control module via serial data message.
AC Compressor has a motor start up procedure that can take a variable length of time to run to bring the motor up to requested speed. Length of time is dependent on external conditions such as under-bonnet temperature and high side pressure. In hotter conditions, the motor start up time will be longer. The A/C compressor control module monitors an internal parameter known as the DC link current which is based off DC input current. It is not possible to measure this parameter externally.