Diagnostic Test

CHECK FOR AN ACTIVE DTC
1. With the scan tool, read HVAC 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 STANDARD PROCEDURE .
CHECK THE HARNESS CONNECTORS FOR PROPER CONNECTION
1. Check for loose, damaged or corroded connections on the Evaporator Temperature Sensor harness connector and HVAC Module harness connector.
  Are there any loose or damaged connectors?
  
  Yes
  - Repair the wiring connectors as necessary.
  - Perform the HVAC MODULE VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  No
  - Go to Step 3.
CHECK THE (C21) EVAPORATOR TEMPERATURE SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND
1. Turn the Ignition off.
2. Disconnect the Evaporator Temperature Sensor harness connector.
3. Disconnect the HVAC Module harness connector.
4. Check for continuity to ground in the (C21) Evaporator Temperature Sensor Signal circuit between pin 2 of the Evaporator Temperature Sensor harness connector and pin 41 of the HVAC Module harness connector.
  Is there continuity to ground in the (C21) Evaporator Temperature Sensor Signal circuit?
  
  Yes
  - Repair the (C21) Evaporator Temperature Sensor Signal circuit for a short to ground.
  - Perform the HVAC MODULE VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  No
  - Go To 4
CHECK THE EVAPORATOR TEMPERATURE SENSOR FOR PROPER OPERATION
1. Replace the Evaporator Temperature Sensor in accordance with the Service Information. Refer to SENSOR, EVAPORATOR TEMPERATURE, REMOVAL AND INSTALLATION .
2. With the scan tool, erase HVAC DTCs.
3. With the scan tool, read DTCs.
  Did this DTC reset?
  
  Yes
  - Go To 5
  No
  - Test complete.
  - Perform the HVAC VERIFICATION TEST. Refer to STANDARD PROCEDURE .
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 MODULE VERIFICATION TEST. Refer to STANDARD PROCEDURE .
  No
  - Repair any faulty connections.
  - Perform the HVAC MODULE VERIFICATION TEST. Refer to STANDARD PROCEDURE .