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Makes 🢒 GMC_Truck 🢒 2007 🢒 Acadia - AWD 🢒 Bulletins 🢒 Rear HVAC Turns On To Full Hot High Blower And Floor Mode When Started - keywords a/c ac air automatic cj2 conditioning control fan intermittent knob

Rear HVAC Turns On To Full Hot High Blower And Floor Mode When Started - keywords a/c ac air automatic cj2 conditioning control fan intermittent knob

Subject: Rear HVAC Turns On To Full Hot High Blower And Floor Mode When Started

Models:2008 Buick Enclave
2007-2008 GMC Acadia
2007-2008 Saturn Outlook
RPO CJ2 without UK6


This PI was superceded to now include the repair information to reprogram the HVAC control module. Please discard PIT4654.

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 rear HVAC system defaults to full hot, high blower, and floor mode when the vehicle is started despite the rear HVAC controls being set to other parameters. This can happen after the following criteria is met.

  1. The ignition has been off long enough to allow the modules to go to sleep.
  2. The (AUX) button on the front control head IS NOT turned on.
  3. The Engine is started.

If each individual rear HVAC control knob setting is changed (Fan Speed, Temperature, and Mode), normal system operation will resume.

Recommendation/Instructions:

Reprogram the HVAC control module with the latest calibration in TIS.

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.