More than likely you have a failed, or failing, blend actuator. If the drivers side changes, and the passenger side is stuck at hot, it is probably defaulting to hot as a result of overtravel. Try removing the HVAC/ECAS fuse in the underhood fuse block, and reinserting it. This performs a recalibration of the actuators. It may come back to functioning as it is supposed to, but at some time may default again. It is in most cases, a faulty actuator, but there can be a condition in the HVAC housing that can also lead to overtravel. If you had a scan tool that could access the HVAC module, you would probably find a code. There has also been some calibration upgrades that could be programmed in the HVAC module to address this concern. This is the bulletin to explain what I am describing.
Subject: Intermittent Ticking Noise from I/P, Poor A/C Performance, HVAC DTCs B0229, B0414, B0424, B3770 (Reprogram HVAC Control Module)
Models: 2004-2006 Cadillac Escalade Models
2004-2006 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2004-2006 GMC Sierra Models, Yukon Models
with Air Conditioning (RPOs CJ2, CJ3)
Some customers may comment on one or more of the following concerns: Intermittent ticking/clicking noise from the instrument panel.
Recirculation mode does not work or Air Conditioning (A/C) system performance is poor during high ambient temperatures.
Unable to control the driver side temperature.
Unable to control the passenger side temperature.
Unable to change the front system modes.
This condition may be caused by the Heating, Ventilation and Air Conditioning (HVAC) actuators that may hunt for the correct commanded position. This cycling may cause a clicking or ticking noise.
An overtravel of the HVAC system control doors may cause one or more of the concerns listed above. If an overtravel occurs, a Diagnostic Trouble Code (DTC) will be set, and the door will go to a preset default position. When a system door defaults, that door will stay at the default position until the DTC is cleared. After the DTC is cleared, the door will operate properly until the overtravel condition re-occurs.
The following table lists the HVAC system doors and the DTC associated with it.
Air inlet door (recirculation door)
Left temperature door
Right temperature door
Front system mode door
Technicians are to perform the normal diagnostic procedures in SI for these concerns. If diagnostics show that the HVAC system door(s) travel below 5 counts (out of the lower range) or above 250 counts (out of the upper range), then update the software calibrations in the HVAC control module. The new calibrations were made available to dealerships as part of TIS2000 incremental satellite update version 2.5, which was broadcast to dealers in February 2006.
The new calibrations have been updated to compensate for the actuator overtravel condition, the actuator hunting and the ticking/clicking noises. The new calibrations effectively eliminate the codes listed above, the default position of the doors associated with the DTCs and opens up the feedback position value. The new calibrations should not be used unless the vehicle has one or more of the customer concerns listed above or a DTC listed above has been set. The new calibrations will not correct any other DTC or A/C system performance concern.
August, 2, 2011 AT 5:49 AM
I will add the service info on the actuator recalibration as well.
Important: Do not adjust any controls on the HVAC control module while the HVAC control module is self-calibrating. If interrupted, improper HVAC performance will result.
Alternate Method (w/o Scan Tool)
Clear all DTCs.
Place the ignition switch to the OFF position.
Install the HVAC actuator.
Connect all previously disconnected components.
Remove the HVAC/ECAS fuse for a minimum of 10 seconds.
Install the HVAC/ECAS fuse.
Start the vehicle.
Wait 40 seconds for the HVAC control module to self-calibrate.
Verify that no DTCs have set as current DTCs.