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Is your system Manual or Auto HAVC ?
Have you tried to retrieve for trouble codes?
DIAGNOSIS AND TESTING - ERRATIC OPERATION OF HVAC SYSTEM
Erratic operation of the A/C and heater systems including:
" Lack of cold air
" Lack of hot air
" Unrequested mode change (ATC only)
" No control of mode or temperature control or tapping blend door noise
These symptoms may be accompanied by the following Diagnostic Fault Codes (DTC's):
" Blend door feedback
" Blend door stall
" A/C Control Mode door input shorted to battery
" In-car temp sensor failure
" ATC messages not received
" Mode door stall
Check for the presence of DTC's with the DRB III(R). If the symptoms and or DTC's listed above are present, perform the following Repair Procedure:
With the vehicle at room temperature 10 to 27 C(50 to 80 F), pull the M-1 fuse for five minutes to erase any DTC's. Replace the fuse and start the vehicle to recalibrate the HVAC system. Operate the vehicle and A/C heater system to verify that symptoms and or DTC's are gone. If tapping noise or blend stall/feedback DTC's re-occur, additional diagnosis will be required.
The M-1 fuse is Fuse # 19 (15 A) in underdash fusebox. It is the one circled in Red.
Thursday, June 3rd, 2010 AT 12:33 PM