Operation CHARM: Car repair manuals for everyone.

Scan Tool Fault Detection

There are two on-screen indications to the user that the HVAC system is not operating properly:
^ If the outside ambient air temperature sensor fails, the set temperature will display (instead of the outside air temperature) when the system is ON.
^ If only °C°F is displayed on the heater and A/C control, this indicates a loss of communication between the Instrument Panel Module (IPM) and the heater and A/C control.