A/C - A/C Not Cold/No Power To The Compressor
SOURCE: Hyundai Tech Net Times Volume 14 Issue 3 2004TITLE: No Power To The A/C Compressor
APPLIES TO: All
SERVICE TIP:
If an air conditioner (a/c) is not blowing cold and there is no power getting to the compressor you can use the Hi-Scan Pro to quickly diagnose the condition. To start, enter the Engine Data menu and scroll down so that you can monitor the "A/C Switch" and "A/C Comp. Relay" (see example top of the next column)
Start the vehicle and press the a/c switch so the indicator on the dash lights up. Next, use the charts to help find the condition based on the Hi-Scan inputs you get from the vehicle being tested.
A. The vehicle's ECU has not received an input from the a/c control head. Use a DVOM and test signal voltage from the back of the a/c control unit to the ECU. If a battery voltage signal is present at the a/c control unit, test for an open in the signal wire or the connection at the ECU. (See applicable ETM)
B. The ECU has recognized the a/c switch input but is not turning the compressor on for a reason. Confirm the coolant temperature is below 240 degrees F by monitoring the ECT on the Hi-Scan Pro. Confirm the a/c system pressure is normal, if okay bypass the Triple Switch by jumping pins 1 and 2 in the harness with the switch unplugged. If the compressor comes on with the switch bypassed there is a pressure problem or the switch is bad. Test the Thermostatic switch in the evaporator according to the appropriate Shop Manual.
C. Check for a ground signal to the compressor relay. If no ground signal is present check the wire for an open between the junction block and the ECU (see applicable ETM). Confirm that two pins at the relay have power with the key on. The relay is numbered on the bottom side. Pins 86 and 30 should both have power. Check for an open wire between the relay and the compressor.