Section 16 (HVAC System - Automatic): Self-Diagnostics: Notes

WARNING: This page is about a different car, the 1997 Oldsmobile Cutlass Supreme. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Diagnostic Trouble Code (DTC) symptoms should be diagnosed and repaired before proceeding with any other tests. DTCs can be retrieved with the A/C-heater control unit.

If a fault has occurred in a monitored circuit, the °F or °C symbol on the A/C-heater control unit display will flash during the first 2 minutes of operation. To enter diagnostic mode, turn ignition on, then press AUTO and OFF buttons at the same time.
There are 2 display modes within diagnostics: diagnostic pointer and diagnostic value. By rotating the FAN knob, one detent in either direction, display is toggled between pointer and value. Rotating TEMP knob will switch the diagnostic pointers.
A/C system DTCs reside under diagnostic pointer 00. Rotate FAN knob one detent in either direction and DTC data will be entered. If more than one DTC is present, they will be displayed at one second intervals. See DTC IDENTIFICATION table. Other data used by computer resides under other diagnostic pointers and is not useful diagnosing A/C-heater system. To exit diagnostics, press any mode button.
After a repair is completed, DTCs must be cleared from memory to ensure proper system operation. To clear memory, press A/C mode button.

NOTE: A 2-digit DTC indicates fault is current. A 3-digit DTC indicates fault is intermittent.

DTC IDENTIFICATION

DTC	Fault
00	No System Faults
01 Or 101	In-Vehicle Air Temperature Sensor Short
02 Or 102	In-Vehicle Air Temperature Sensor Open
03 Or 103	Outside Air Temperature Sensor Short
04 Or 104	Outside Air Temperature Sensor Open
05 Or 105	Left-Side Temperature Valve Actuator Open Or Short
06 Or 106	Right-Side Temperature Valve Actuator Open Or Short
07 Or 107	Serial Data Line Fault
08 Or 108	Passenger-Side A/C-Heater Control Short
09 Or 109	Passenger-Side A/C-Heater Control Open