Rear HVAC System May Come On Unexpectedly - keywords A/C AC blower control heat heater intermittent unwanted

This PI was superceded to change the recommendation to do not make any repairs. Please discard PIT4335A.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

The Rear HVAC system may come on unexpectedly. This condition may occur on vehicles with either a Front Manual or Front Automatic HVAC controlled system combined with a Rear Manual HVAC control (non-RSA). This concern is most likely to occur when the Rear HVAC control knobs are placed "in-between detents".

Do not make any repairs for this concern at this time. Engineering is aware of the concern and is working on a fix. This PI will be updated when a fix becomes available.

The system should remain functional. Advise the customer if the system turns on unexpectedly to turn the Rear HVAC system off (via AUX button on front control head or Fan knob to OFF on rear control). Since this concern is most likely to occur when the Rear HVAC control knobs are placed "in-between detents", advise the customer to make sure the rear control knobs are set on the detents. This should minimize/eliminate the potential of this occurring.

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.