Need Help Please

[myPepper]

I have a 2004 Cayenne S, when I put the heat on I have heat on the drivers side and cold air on the passenger side. It does not matter what I set the passsenger side to, ie, HI heat recirculate, it blows cold, so I just turn it off. I recall I get the reverse effect in the summer, Ice cold for the drivers side when I want it cold, but still hot on the passengers.

Anyone have any clues as to what this could be before I spend my lifes savings at the stealership?

[mudman2]

It sounds like one of 2 things, either the servo's on the passenger or the AC control unit it dead or on its way out. On an 04 its highly lightly is the AC electronic head unit if its not already been changed there were many instances of bad ones

[rizzo]

My 04S does the exact same thing...

Quite frustrating as there are twelve different servos controlling when and where the conditioned air goes.

If I knew which servo motor controlled the right side I would replace it myself.

Most of the time, if I set the heater controls above 75 degrees F on both sides, the right side will begin to blow warm air. Usually no more than ten to fifteen minutes after car start.

mudman2, is it your belief that this is related more to the electronic controller vs a servo motor? I ask because the "gerbils" become quite active when I switch to heat vs cold. Makes me think the controller IS sending the signal but the servo motors are going full "crack addicted gerbil" mode.

[mudman2]

I think the hamsters start to run around when the controller gets confused as to what temperature blows where.

Its hard to believe that all hamster driven servo's failed on one side, it points to a more central issue I feel. i think every output should be surveyed to make sure they are really off since the lower ones hardly blow at all

[myPepper]

I did want to mention sometimes after 15 minutes or so the passenger side begins to work normally. Once it works, it works the rest of that ride, but each time I get back in, I never know if the passenger side is going to blow cold in the winter or HOT in the summer even when the AC is on full blast. Also I have the digital thermostat controls in the back console as well and yes right rear is off like passengers.

I'm pretty mechanically inclined, so if anyone knows a DIY please let me know. Thanks!

[mudman2]

I think I would try to get a PIWIS reading on the system prior to buying anything, it may be able to pinpoint the AC Controller or specific failed servo's. Worth a couple of hundred $ because ripping out the servos is a PIA

[rizzo]

The last few times this has happened to me I have done the following...

Push the front windshield defroster button with the temperature selectors on "high" for both sides. This places the fans on high and directs all flow to the windshield vents.

After a minute or two of hurricane force winds I've pressed the same front windshield button again. That turns off the defrost configuration and places the vents back to the pre-defrost configuration (whatever that may have been).

Each time I have done this now it has resulted in warm air (what I needed and wanted) blowing on the passenger side when it was blowing cool (not what I wanted) before.

I'll keep trying this before I go to the dealer for some high dollar hamster driven servo motors.