P1EC9 – A/C Compressor Motor Instantaneous High Current

P1EC9 Possible Symptoms

Engine Light ON (or Service Engine Soon Warning Light)

P1EC9 Possible Causes

Faulty A/C Compressor Motor,A/C Compressor Motor harness is open or shorted,A/C Compressor Motor circuit poor electrical connection

P1EC9 Description

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 speed request message is sent from the Hybrid/EV Powertrain Control Module 2 to the A/C compressor control module via GM LAN message.