Without Scan Tool

The heater and A/C programmer contains self diagnostics that, when accessed with the scan tool, are designed to identify the source of any system malfunction as specifically as possible, including whether or not the malfunction is current or the non-current (history) type.

The letter H after any of these DTCs indicates a history code. Example: DTC B1310H = History.

Displaying Diagnostic Trouble Codes (DTCs)

The diagnostic trouble codes (DTC) set by the HVAC programmer can be displayed by the "On-board" method.

1. Press and hold the OFF, AUTO, and RECIRC buttons for one second.
2. The DTCs will display for two seconds each, and then return to normal operation.