Visitoron May 9, 2011
if u want an answer u need to rephrase question , says cant change from hot to cold but its cold all the time, dont know if its always hot or always cold, cold on heat -hot on cold etc.
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
A dealership should perform the following tests. Check for the presence of DTC's with the DRB III®. 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. An A/C Performance and Heater Performance test should also be performed. Inadequate cooling could be from a low refrigerent level in the A/C system, Condensor fan operation etc. Heater Performance could be Pinched or kinked heater hoses. Improper heater hose routing.
Plugged heater hoses or supply and return ports at cooling system connections, Plugged heater core. Air locked heater core.
If coolant flow is verified and outlet temperature is insufficient, a mechanical problem may exist.
POSSIBLE LOCATION OR CAUSE OF INSUFFICIENT HEAT
Obstructed cowl air intake.
Obstructed heater system outlets.
Blend door not functioning properly.
Low coolant level
Air locked heater core or air in cooling system
TEMPERATURE CONTROL
If temperature cannot be adjusted with the TEMP knob/button on the control panel, the following could require service:
Blend door binding.
Faulty blend door actuator.
Improper engine coolant temperature.
Faulty A/C Heater Control.
for several months heater would only blow cold air. Had it checked told it was a ECU failure. now that its warmer tried running air conditioner now it blows warm air all the time.