ILCUL8R

'09 Cayenne GTS... I have a problem with the ventilation fan (I think).
Here is the scenario:
Start vehicle, temp set to 72, fan speed on 3 notches, distribution set to front panels and foot well. Notice that there is hardly any air coming out of vents. Lower temp--- same result. Raise fan speed all the way up --- same result. Switch to ECON mode--- same result. Change distribution ---- same result. Finally I lower temp to LO setting and fan now kicks on full blast. (as it should in this mode) Lower fan speed and set temp back to 72. Everything ok for 15 min. trip. Park vehicle.
Come back two hours later, start it up, now it decides to work as it should. Now drive 10 minutes. Stop at store for 5 minutes. Start back up...same problem again.
Seems only way to get fan to kick in again is to bring temp back down to LO and then it will work. Obviously an intermittent problem.

Any one have this problem or any ideas ??

Thanks.

wrinkledpants

If you leave the HVAC on Auto, does it ever start working correctly - like after a minute or two? What are the outside temps when this is happening?

deilenberger

Indeed. The "AUTO" setting keeps the fan from blasting cold air on you when you have a cold cooling system, and the temperature outside is below some level (not sure what level - but it's been in the 20's the past day here - and it's not turning the fan on until the engine shows some temperature.)

It's a feature. If you don't want that to happen, turn it off AUTO and just set the fan speed where you want it. I think (dunno for sure - since I've found auto to work perfectly for me) - it won't do that. One other thing to try - press the defogger button - fan should come on full-speed no matter what the temperatures are, blowing all the air at the windshield.

ILCUL8R

Setting to Auto did not resolve problem. Outside temp was approx. 62 at the time. First time it occurred outside temp was 75. (BTW, I always run system not in AUTO mode)
I will try defogger button tomorrow to see what happens...

wrinkledpants

I would check your battery first. The car won't let the HVAC fan run right away until the voltage gets to a certain point. If you have an aging battery, that can sometimes take awhile.

I haven't heard of these symptoms before, so my guess is that it has something to do with the HVAC control unit, or the fan relay. You could try replacing the relay to see if that helps. My guess is this would take a lot of troubleshooting to know for sure since the symptoms are intermittent.

ILCUL8R

Hmm, battery could be the answer perhaps as it is the original. Meanwhile, I tried setting it to defog (defrost) windshield and while the fan indicator went into all the way up there was barely anything coming out of the vents by the windshield.
So once again knocked the temp down to LO and wham air was flowing big time.
I set it back to normal temp of 72 and it moved air out of dash and floor vents.
( I also noticed that even if I turn off dash vents there is still air coming out them)
AND on way home just now, it stopped moving air again but this time while driving.
Naturally, this was just at the dealer for service on another issue... so back I go.

p.s. Fan relay getting screwy could make sense as well.

wrinkledpants

If the control unit is requesting air (your bars are maxed out on), then I have to believe it's probably the relay.

If you don't do any work yourself, then I would just let the dealer handle it. If you do, the relay is down under the kick panel on the passenger side. Not super difficult to change.

ILCUL8R

Thanks for the help and suggestions. Here's the resolution:
Two techs worked on it and they found that there is a rod that moves into position to open the flaps for the vents when the vehicle is started. It's way up in the back dash area behind the glove box. Apparently it was not connecting to another rod when the normal temp is selected. When you go to LO it swings it all the way over and it engages. But when vehicle is shut down and started again the whole process starts all over again. One tech was able to worm his way up in there and reconnected it properly w/o having to pull the dash or glove box ! Now the beast is working correctly again.
As to the battery, I decided to have it replaced anyway since it's no longer holding the correct amperage level due to age. Can't complain as this was a CPO that I got in 2011 and it is the original battery, so 6 1/2 years is pretty good I'd say ! Don't want to get stranded out of the blue somewhere.
Half the cost, as you know, is the labor since it's under the driver's seat. But at least that way it's not in the hot engine compartment.
Soooo, that's it on this one.