With Scan Tool

The heater and A/C programmer contains self diagnostics that, when accessed with a 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.

There are 14 HVAC diagnostic trouble codes (DTCs) to assist with diagnosis.

The letter H after any of these DTCs indicates a history code. Example: DTC 010H = History, DTC 010C = Current.

The only way to display diagnostic trouble codes (DTCs) is by using a scan tool.