Alternate Diagnostic Methods - HVAC Module - Electronic Automatic Temperature Control (EATC) and HVAC Module - Dual Automatic Temperature Control (DATC): Notes

The EATC and DATC system must be diagnosed by first retrieving any DTCs, if present.

• An on-demand (hard fault) DTC indicates that the fault is currently present. An on-demand DTC suggests a wiring fault, disconnected connector or component failure.
• A continuous (intermittent) DTC alone (corresponding on-demand DTC is not present) indicates that the fault is an intermittent condition and may not be currently present. A continuous only DTC suggests a poor wiring connection, loose pin or terminal or intermittent component failure.

On-demand (hard fault) or continuous (intermittent fault) DTCs can be retrieved using a scan tool. If using a scan tool, refer to the scan tool operating manual.

On-demand DTCs can also be retrieved by carrying out the HVAC Module - Electronic Automatic Temperature Control (EATC) and HVAC Module - Dual Automatic Temperature Control (DATC) On-Demand Self Test. To retrieve and/or clear continuous DTCs, carry out the HVAC Module - Electronic Automatic Temperature Control (EATC) and HVAC Module - Dual Automatic Temperature Control (DATC) - Retrieve Continuous DTCs procedure. Always retrieve both on-demand and continuous DTCs before proceeding with diagnosis and/or repair.

If no on-demand or continuous DTCs are present, go to Symptom Chart - Climate Control Systems  for the appropriate diagnostic action.