944S2 cabrio interior fan permanently on!

944cabrio · 02-20-2012, 12:36 AM

Hello everyone,
my 91 cabrio had a night parked outside in the rain , pointing backwards down a slope. When I tried to start it, the battery was completely flat.
After a recharge, the interior fan could be heard turning without the key even in the ignition.
Also the electric roof, and windows could be operated with the key out!
I pulled the fuses one by one until fuse number 29, where I thought the fan had stopped turning, but it turns out that the fan is still turning but much slower.
I only get to the car at weekends so would appreciate any ideas for an efficient fix.
Many thanks, from Paris, France

Cocacolakidd · Cocacolakidd's Garage

All is normal - The windows and top can be closed when the key is out - normal feature of our 944's. The Heating and AC controls are very sensitive, so when the system senses condensation in the cab the fan will run at a very slow speed to clear fogged windows, this is when with or without the key, and when the system is on or off. Porsches do things like this -

Have pfun -

944cabrio · 02-20-2012, 05:42 AM

I have to say firstly thanks for the reassuring advice and secondly that I am surprised that Porsche would have a system that would allow the ventilation to run independently and still allow the battery to run flat!
Very crafty zee Germans!
However your explination does make sense, as a few weeks ago the interior fan was running quickly and last weekend, when I reconnected the battery, slower. With the car in the garage things must have dried out a bit.
I'll put a warm air dryer in the car next time overnight and hopefully that will cure the problem.
Has Porsche invented anything to get rid of furry mold on the steering wheel?

Thanks again,
Philippe

Cocacolakidd · Cocacolakidd's Garage

That Furry Mold was what the cabin fan was supposed to help, evidently you have an exceptional case of it. Try wiping down the steering wheel with diluted bleach (Dilution strength at or about 75% water and 25% bleach). Then wipe the bleach clean with a couple of clear water cleanings - the bleach will kill the mold...

944cabrio · 04-14-2012, 02:37 AM

Unfortunately, the problem has come back again. After one night out, the battery is nearly flat and the interior fan was running very slowly. Can anyone please tell me where I can locate the interior sensor so that I can replace it?
Many thanks,
Philippe

944 Ecology · 04-14-2012, 03:56 AM

When the key is out of the ignition, the interior fan should not run under any circumstances. Any speculation that there is a humidity sensor that turns on the interior fan is pure BS.

Of course, I can be persuaded in another direction if there is some factory publication or wiring diagram that shows otherwise.

marko · 04-14-2012, 04:46 AM

Also, you should not be able to operate the cab top with the key out.

944cabrio · 04-16-2012, 10:47 PM

I've been monitoring this problem for a few days now and here is the latest situation.
The weather has been warm and dry during the day, but cool and a little damp during the night.
Running the car during the day and everything is fine. The interior fan works normally and the windows only operate when the key is in the ignition and on position 1.
My inline ammeter is reading 0.05 amps, so everything is fine.
Locked the car and the led warning lamps flashed away happily.
This morning it was damp and I could hear the interior fan turning on its lowest position.
The leds were still flashing. With the car open, and the key NOT in the ignition, I could operate the windows and turn up or down the interior fan, and use the demist function.
The battery still had enough power to start the car.
This time the car was drawing 5 amps.
I've unhooked the battery and will connect it up again after the car has sat in the sun a while.
Thank you for all the advice so far, but if someone can shed any more ideas on where the problem could be coming from, I would be very grateful. At the moment, I cannot trust using the car. Many thanks, Philippe

kfray · kfray's Garage

On the USA model there is a set of contacts on the ignition switch that senses if the key is in the ignition, which could be stuck closed. I sprayed some WD40 in the ignition key slot and worked the key in and out which corrected my problem. On the USA version there is a buzzer which warns if the key is left in the ignition and the door is open.