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

This PI was superseded to advise not to reprogram HVAC if prior programming was performed after June 7th 2008. Please discard PIT4654A.

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

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.

A TIS2WEB calibration was release on June 7th 2008 for the HVAC/Climate Control Panel to correct this concern. Prior to updating the calibration in this module, review the customers repair history for any repairs that involved reprogramming the HVAC/Climate Control Panel on or after June 7th 2008. If the HVAC/Climate Control Panel has NOT been reprogrammed on or after June 7th 2008, reprogram this module using the latest calibration in TIS2WEB. If the HVAC/Climate Control Panel HAS been reprogrammed after June 7th 2008, do not reprogram this module again. Follow published diagnostics.

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.