HVAC Module - Diagnostic Methods
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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 carry out the HVAC Module On-Demand Self Test before retrieving continuous DTCs.
If no DTCs are present, GO to SYMPTOM CHART - CLIMATE CONTROL SYSTEMS for the appropriate diagnostic action.