| Subject: | Erratic Operation Of Manual Dual Zone HVAC |
| Models: | 2004-2007 Buick Rainier |
| 2002-2007 Chevrolet Trailblazer, Trailblazer EXT and Trailblazer SS |
| 2002-2007 GMC Envoy, Envoy XL, Envoy XUV and Envoy Denali |
| 2002-2004 Oldsmobile Bravada |
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Some customers may comment that the manual dual zone HVAC is erratic. Air outlet temp will be either full hot or full cold, actuators can not be controlled to midpoints. Monitoring the Tech 2 HVAC data, "Desired" and "Actual" positions for both temp actuators
do not travel together and are reversed in counts. This may be the result of the passenger temp actuator installed on the driver's side of the case and/or the driver's actuator is installed on the passenger side of the HVAC. This may occur after the vehicle
was serviced for this concern and the wrong actuator was installed in the wrong position.
Recommendation/Instructions:
Using the Tech 2, monitor the commanded and actual values for the suspected actuator. If the values are opposite of each other for the actuator in question, suspect the wrong actuator was installed. Replace the actuator as needed.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
