Circuit/System Testing
Ignition OFF, disconnect the harness connector at the appropriate actuator.
Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit terminal 1 and ground.
If greater than 1 ohm, test the low reference circuit terminal 1 for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module.
Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 3 and ground.
If less than 4.8 volts, test the 5-volt reference circuit terminal 3 for a short to ground or an open/high resistance. If the circuit tests normal, replace the HVAC control module.
If greater than 5.2 volts, test the 5-volt reference circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the HVAC control module.
Verify the appropriate scan tool parameter is less than 5 counts.
If greater than 5 counts, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the HVAC Control Module.
Install a 3-amp fused jumper wire between the signal circuit terminal 3 and the low reference circuit terminal 1.
Verify the appropriate scan tool parameter is greater than 250 counts.
If less than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module.
Connect a test lamp between the control circuits terminal 4 and 5 of the applicable actuator.
Command the actuator in both directions with a scan tool. The test lamp should turn ON and OFF with each command.
If the test lamp remains always ON or always OFF during either of the commands, test both control circuits for a short to voltage, short to ground, or an open/high resistance. If the circuit tests normal replace the HVAC control module.
Ignition ON, after 30 seconds verify that a test lamp illuminates between control circuit B terminal and B+.
If the test lamp does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal replace the HVAC control module.
Ignition OFF, verify that the test lamp does not illuminate between control circuit B terminal and B+.
If the test lamp illuminates, test the control circuit for a short to ground. If circuit tests normal replace the HVAC control module.
If all circuits test normal, test or replace the appropriate actuator.
Repair Instructions
NOTE:Always perform the DIAGNOSTIC REPAIR VERIFICATION - VEHICLE DIAGNOSTIC INFORMATION after completing the diagnostic procedure.
CONTROL MODULE REFERENCES for HVAC replacement, setup, and programming.
RECIRCULATION ACTUATOR REPLACEMENT
MODE ACTUATOR REPLACEMENT
AIR TEMPERATURE ACTUATOR REPLACEMENT
AUXILIARY AIR TEMPERATURE ACTUATOR REPLACEMENT
AUXILIARY MODE ACTUATOR REPLACEMENT
Apr 30, 2010 at 4:31 AM
