Diagnostic Test

CHECK FOR AN ACTIVE DIAGNOSTIC TROUBLE CODE (DTC)
1. With the scan tool, read HVAC Diagnostic Trouble Codes (DTCS) and record on the repair order.
2. Record the Environmental Data.
3. With the scan tool, erase DTCs.
4. Using the recorded Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
5. With the scan tool, read HVAC DTCs.
  Did the DTC return?
  
  Yes
  - Go To 2
  No
  - Perform the INTERMITTENT CONDITIONS TEST. Refer to TESTING FOR AN INTERMITTENT CONDITION .
PERFORM HVAC ACTUATOR CALIBRATION TEST
1. With the scan tool, perform the HVAC Actuator Calibration Test.
  Did this DTC change from Stored to Active while performing the HVAC Actuator Calibration Test?
  
  Yes
  - Go To 3
  No
  - Perform the INTERMITTENT CONDITIONS TEST. Refer to TESTING FOR AN INTERMITTENT CONDITION .
CHECK THE (C27) A/C COMPRESSOR CONTROL CIRCUIT FOR A SHORT TO VOLTAGE
1. Turn the ignition off.
2. Disconnect the HVAC Module C1 harness connector.
3. Disconnect the A/C Compressor Solenoid harness connector.
4. Turn the ignition on.
5. Measure the voltage on the (C27) A/C Compressor control circuit at the A/C Compressor Solenoid harness connector.
  Is there any voltage present?
  
  Yes
  - Repair the (C27) A/C Compressor control circuit for a short to voltage.
  - Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  No
  - Go To 4
CHECK THE (C27) A/C COMPRESSOR CONTROL CIRCUIT FOR AN OPEN
1. Turn the ignition off.
2. Measure the resistance of the (C27) A/C Compressor control circuit between the HVAC Module C1 harness connector and the A/C Compressor Solenoid harness connector.
  Is the resistance above 3.0 Ohms?
  
  Yes
  - Repair the (C27) A/C Compressor control circuit for an open or high resistance.
  - Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  No
  - Go To 5
CHECK THE A/C COMPRESSOR
1. Diagnose the A/C Compressor in accordance with the Service Information. Refer to DIAGNOSTIC CODE INDEX .
2. With the scan tool, erase DTCs and perform the HVAC ACTUATOR CALIBRATION TEST.
  Did the DTC return?
  
  Yes
  - Go To 6
  No
  - Test complete.
  - Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
CHECK RELATED HARNESS CONNECTIONS
1. Disconnect all HVAC Module harness connectors.
2. Disconnect all related in-line harness connections (if equipped).
3. Disconnect the related component harness connectors.
4. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions: Proper connector installation. Damaged connector locks. Corrosion. Other signs of water intrusion. Weather seal damage (if equipped). Bent terminals. Overheating due to a poor connection (terminal may be discolored due to excessive current draw). Terminals that have been pushed back into the connector cavity. Perform a terminal drag test on each connector terminal to verify proper terminal tension. Repair any conditions that are found.
5. Reconnect all HVAC Module harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
6. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
7. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
8. With the scan tool, erase DTCs.
9. Using the recorded Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
10. With the scan tool, read HVAC Module DTCs.
  Did the DTC return?
  
  Yes
  - Replace the HVAC Module in accordance with the Service information. Refer to MODULE, HVAC, REMOVAL AND INSTALLATION .
  - Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  No
  - Perform the HVAC VERIFICATION TEST. Refer to HVAC VERIFICATION TEST .
  - Test complete.