No Heat Unless Automatic HVAC Control Module Is Turned To 90F - keywords A/C AC air ambient blows cold head high hot inop inoperative module remote RVS sensor setting start temp temperature

This PI was superseded to update Condition/Concern. Please discard PIC4390.

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

On vehicles built between the VIN range of 7F211644 to 7F220167 may have a customer complaint that there is NO heat coming out of the Automatic HVAC system. There with be NO heat unless the temperature is set to 90F on the control head (90F is highest setting).

If the temperature is set at any other setting then ambient temperature is provided.

Using the Tech 2 verify what the Inside Air Temp. Sensor is reading. Under the Body section select the following choices:

HVAC Control Module > Data Display > Sensor Data > Inside Air Temp. Sensor.

If the temperature reading for the Inside Air Temp Sensor is greater than what the current interior temperature should be. (reading may be as high as 176F)

Replace HVAC control head.

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.