Few days ago, checked 2004 CTT in the morning and saw that alarm LED in the front door wasn't blinking. Then the car won't start with plastic fob. Somehow, it started by putting the key in the slot and clock was showing 12:00. So, looks like battery depleted and hence, goose chase for seeing what's causing the drain.

Later that evening I noticed that HVAC fan keeps running even if the car is shut off. When the car is on, fan speed responds to the switch setting but keeps running if I hit off. The only way to stop this is to pull the fuse for few seconds and put it bac in. Problem came back today and had to pull the fuse out again.

So, what might be causing this? Some sort of faulty HVAC control?
thanks much in advance.

 

Probably the HVAC control, or the control on the fan itself. That's a "probably" - without troubleshooting with a voltmeter it's hard to give a definite answer. The other question area when electronics go odd on a Cayenne - is the wiring under the footwell carpeting on both sides front. That wiring is prone to damage that can cause very odd things to happen as electrons swap circuits where they shouldn't. Flooding of the footwells due to plugged drains is the root cause. This is only found by pulling the carpeting up and unwrapping the wire harnesses looking for green corrosion from soaked splices.

 

There's a feature in the HVAC that lets you recover heat from the engine into the passenger compartment, even with the engine off - I don't recall the name of the button, but i'ts in the manual (at least in my 09 Turbo S). Maybe that button is stuck down or on or something, but with your other issues, could be low battery or the wet wiring Don mentions.

 

I would start with investigating and/or replacing the regulator:
http://www.pelicanparts.com/More_Inf...SABEgJLX_D_BwE

 

It's "Rest" button - should have the "Rest" displayed on lower screen if activated and should auto shut off after some minutes.

 

Thanks for the suggestions folks, appreciate it.

It's not related to "Rest" as that was the first thing that came to mind.
Noticed two more things:
I did bit more testing and saw that fan keeps running even if I manually turn off the HVAC control (keep pressing fan speed button down) and car is ON.
One thing I noticed is that if I run HVAC at the highest temp and full fan speed for few mins, it seems to turn off.

I will start with pulling back carpet to see if water is causing any wiring shortage and then replace regulator.

 

It is always good to check under the carpet on these things since it seems most will eventually get water there, but I am pretty sure it is the regulator.

I had a very similar issue and replacing it fixed it for me:
1. Turning the fan to the highest setting, it would change to various speeds on its own intermittently, but at all other speeds seemed to work fine.
2. Sometimes turning off the car it would stay running, but slowly, slowly wind down after 2-5 minutes and eventually stop.
3. Sometimes the fan would keep running even when I turned the fan to 'Off'

It appears to me the failure of yours is just a little more advanced or severe as mine never killed the battery. It was just a small annoyance for a few weeks until I quickly addressed it.

 

Also, FYI - There is a story on here of someone who had their regulator/motor go haywire and it burned up a large section of their wiring harness in the dash resulting in a very difficult and expensive fix. I believe it was Cordsig.

 

Is JL a good brand or should I get the OEM version for 180$?

 

I used the one from the link on pelican I posted earlier and it is working fine.

 

Its probably just the fan regulator behind the glovebox. I had the same problem you had with it running and killing the battery. Regulator fixed it. Pelican has a write up under the blower motor section. They are available on Amazon and pretty cheap. Also they are blue in color.

 

Cars is mostly parked indoors and it has been dry in Seattle for the last couple of weeks. I used a flashlight to look through the footwell area but did not see any signs of moisture or water. I scanned the car with Durametric yesterday and did saw an error code regarding the regulator.
I ordered the part yesterday from pelican; should be here tomorrow to install. Hopefully, this will fix the issue.

thanks for all the suggestions.

 

The advise was spot on. Got the new part from pelican today, installed it and seems to be working well.

 

I appreciate Petza914 mentioning the heat recovery feature. My wife just called me freaking out that the cabin blower motor wouldn't stop when she parked the car while shopping. She also said the auto temp was set at 83. I put two and two together after finding your answer having read about that odd feature in the manual. She'd hit the recovery system button. Turned off and all is well. Thanks!!!

 

Does anyone know where the circ pump relay and residual heat relay is located?