Section 10 (HVAC System - Automatic): Self-Diagnostics: Notes

WARNING: This page is about a different car, the 1996 Oldsmobile Cutlass Supreme and 1996 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Trouble code symptoms should be diagnosed and repaired before proceeding with any other tests. Trouble codes can be retrieved with the A/C-heater control.

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 same time. See Figure.
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.
Diagnostic Trouble Codes (DTCs) reside under diagnostic pointer 00. Rotate FAN knob one detent in either direction and trouble code data will be entered. If more than one code exists, they will be displayed at one second per fault. See TROUBLE CODES table. Other data used by computer resides under other diagnostic pointers and is not useful in diagnosing A/C system. To exit diagnosis, press any mode button.

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

TROUBLE CODES

Code Number	Symptom
00	No System Faults
01 Or 101	In-Car Air Temperature Sensor Short
02 Or 102	In-Car Air Temperature Sensor Open
03 Or 103	Outside Air Temperature Sensor Short
04 Or 104	Outside Air Temperature Sensor Open
05	Left Electric Actuator Open or Short
06	Right Electric Actuator Open or Short
07	Serial Data Line Failure
08	Passenger A/C-Heater Control Short
09	Passenger A/C-Heater Control Open

NOTE: If Codes 01, 03 and 08, or Codes 02, 04 and 09 are set, check Brown wire between A/C-heater control and splice. If circuit is okay, replace A/C-heater control.