Central air vents have failed.

[PanzerTT]

Hello,

I have an '04 Cayenne TT and the central air vents, above the PCM, have ceased in blowing air completely. I haven't pulled the codes, no Durametric etc., but the servo motors are suspect, IMHO. There is now complete silence, you used to hear the clicks and whirring noises but that ceased when the vents stopped blowing.

After reading the tech manual, it states that the PIWIS is needed to reset the limits of the motors after installation. It also states in the absence of the PIWIS, you may use 12 volt power in order to do this.

What I am getting at is that I really, really, want to save a trip to the stealership. Either I want to replace the servos or have my indie shop do this (however, they have no PIWIS).

I am pretty competent do it yourselfer but need some thoughts or guidance, if one is able and willing?

Thanks for your help.

[XR4Tim]

Servo motor(s) are probably the culprit. You are supposed to use the PIWIS tester to put all of the servo motors in "service position" before replacing any of them, so that the control unit knows what position they are all in when you are done. New servo motors come preset in this service position. What I would do, is replace the servo motor, and see if it works. If not, disconnect the battery for a while, hook it back up and see if the system recalibrates itself. If that doesn't work, then you can take it to the dealer and just have them do a servo motor calibration. The calibration takes about a minute to do with the PIWIS, so they shouldn't charge an arm and a leg for it.

[west912]

I have a similar but different problem in that my fans blow air, but the passenger side is cold air and the drivers is hot air, when both zones are set to hot.

It is intermittent in that it wil eventually revert back to both blowing hot air after a few days of not changing the setting, but if I change the temp to cold for any length of time, then the problem comes back.

Where are the servo motors that switch the hot and cold air flow located. Can any one give me some advice? Is it strictly a dealership repair?