Alternate Diagnostic Methods - HVAC Module: Notes

The HVAC 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 On-Demand Self Test. To retrieve and/or clear continuous DTCs, carry out the HVAC Module - Retrieve Continuous DTCs procedure. Always retrieve both on-demand and continuous DTCs before proceeding with diagnosis and/or repair.

If no DTCs are present, GO to SYMPTOM CHART - CLIMATE CONTROL SYSTEMS  or GO to SYMPTOM CHART - NVH  for the appropriate diagnostic action.