This is for auto HVAC which is equipped with self diagnostic.
If all the lights come on on climate control panel but button lights and display lights can't set temperature the control head is bad and needs to be replaced
1. Set A/C-heater control panel to display degrees Fahrenheit. Start engine (vehicle not moving) and set temperature control to 75 F. To enter self-diagnostic mode, simultaneously press and hold floor, mix, and defrost buttons.
See Fig. above .
When ATC panel display begins to blink, release all 3 buttons.
2. The display will continue to blink until it completes its tests and calibrations. Any ATC-related diagnostic trouble codes stored in BCM will be displayed when blinking stops. If there are no trouble codes, system will return to normal operation.
3. Trouble codes will appear on display in numerical form. Only one number will be displayed at a time. Press panel (vent) button to scroll through any additional trouble codes.
See DIAGNOSTIC TROUBLE CODES table for list of codes. Exiting Self-Diagnostics & Clearing Codes To exit self-diagnostics, turn ignition off. To clear codes, disconnect negative battery cable for at least 10 minutes.
DIAGNOSTIC TROUBLE CODES
NOTE: If in-vehicle temperature sensor is disconnected while it is operating, Code 26 will set and automatic A/C-heater control panel display will go blank. To correct condition, clear Code 26 from BCM. See EXITING SELF- DIAGNOSTICS AND CLEARING CODES.
Code Affected Circuit/Sensor
23 ATC Blend Door Feedback Failure
24 ATC Mode Door Feedback Failure
25 Ambient Temperature Sensor
26 ATC In-Vehicle Temperature Sensor
27 Sun Load Sensor Failure
31 ATC Recirculation Door Stall Failure
32 ATC Blend Door Stall Failure
33 ATC Mode Door Stall Failure
34 Engine Temperature Message Not Received
35 Evaporator Temperature Sensor Failure
36 ATC Panel Communication Failure
NOTE: For HVAC plenum 10-pin connector terminal identification, see Fig. below.
Please let us know if you need anything else to get the problem fixed.
Thursday, September 4th, 2008 AT 8:22 AM