LSR

If anyone has a clue about what might be causing the front radiator fans of my 2013 Carrera S to have a mind of their own, please let me know. So far, I'm stumped. Here's what's going on:

After I've driven the car, parked it in my garage and shut off the engine, everything seems fine for about 10-15 minutes. But sometimes (though not always), all of a sudden for no apparent reason both front radiator fans turn on hard. This happens even though (1) I did not drive the car hard (just around town for 20 minutes or so at around 30 mph), (2) the weather is cool (low 50s), (3) the car's temperature gauges don't get higher than the low range of normal, and (4) none of the fans (back or front) were on when I shut down the engine. The really weird thing is the fans instantly stop when I open the driver's door! If I close the door again and wait, about 10-15 minutes later the fans might start up again (sometimes they do, sometimes they don't). Today, the fans turned on 3 times before I finally got them to turn off (by opening the door) and stay off. See the attached video showing both fans are on (you can hear each one) and how they shut off just by opening the driver's door.

Has anyone experienced anything like this and/or know the cause and solution? I'm thinking the fan controller might need to be replaced, but that's just a guess. Of course, I could take the car to the dealer and let the techs figure it out. But unless the car has thrown a code allowing for a quick diagnosis (I don't have a reader), it could cost a ton to diagnose an intermittent problem that I have not yet figured out how to trigger on command.

noddy981

I have a similar problem with my 981 Cayman. With no key in the ignition, every time I close the door the right side fan comes on full blast for a few seconds - even with the car not started for 12 hours or so! Both fans work with the aircon on. Did you find the answer or are you still looking/

Porschex3

I posted about this in the Cayenne forums and no one knew the answer. It's the relay controlling the fans. This happened in my 2016 Cayenne (to the point where it would drain the battery completely) and the dealer had it for weeks and couldn't diagnose it. Finally, I made them change out the relay (which was the consensus on the most likely culprit). After changing out the relay it has been fine ever since. Good luck!

Rich_Jenkins

No clue.

Historically, weird electrical stuff on my German cars has usually been associated with a battery on the way out. You have a 2013? When was the battery replaced?

Hope you figure it out.

noddy981

Thanks for the replies. I guess I will have to fish around and unhook the relay carrier from under the dash and change the left and right relays over in an attempt to see if it is a faulty relay.

Keep safe and thanks again

Porschex3

Good luck. This was very frustrating to me because I travel a lot and was very concerned that I would come back to a car that had run it's battery out while I was away. Also, it was quite scary to have the fan start up at full blast in the middle of the night one evening. My Cayenne had the same exact symptoms right down to opening and closing the door would temporarily stop the fan. The dealer was baffled by it until we replaced the relay.

LSR

I did not find the cause, but the problem seemingly has gone away (at least for now). I have driven the car several times since my post and, after a few days of driving and not using the battery maintainer, the fans stopped acting up. While I do not know the cause for certain, my current working theory is it's due to an old battery combined with my having used Porsche's charger/maintainer over the winter. I believe the charger/maintainer caused the battery to produce and maintain an elevated system voltage that the fan controller or relay did not like. After I started driving the car and stopped using the charger when the weather turned warmer, the fan situation continued for a few days but then everything returned to normal once (I believe) the battery's voltage returned to normal. The battery is old - over 6 years at this point - and that may be why this is happening now. This is the simplest explanation I can come up with for why (1) the fans started running after the car was shut off when the car had been on the battery charger, and (2) the fans stopped running when I opened a door. When the door was opened the interior and instrument cluster lights came on causing the system voltage to drop due to the additional load, and the decreased voltage level removed the over-voltage condition that triggered the fan controller or relay. At least, that's my theory.

You're right - your situation seems similar to mine. But it's the reverse - your front right fan (rather than both) starts (rather than stops) when you close (rather than open) the door. But the root cause may be the same. How old is your battery and what is it's condition? Did you use a battery charger/maintainer over the winter? Does the problem always occur or only sometimes? If only sometimes, can you identify what conditions changed? If you close the door and the fan starts, what happens when you open the door again while the fan is running? Right after the fan stops, if you opened and closed the door again does the fan start up again? Rich-Jenkins has observed that weird electrical problems occur with his German cars when the battery gets old. And Porschex3 says the problem in his case was a bad fan relay. If you can narrow down the conditions that result in your fan turning on, you might be able to zero in on the likely cause to avoid replacing parts *****-nilly and the resulting expense. Good luck - please post to let us know how things turn out for you.

noddy981

Thanks for your help. I will come back once I get it sorted.

waizc2s

I had a similar issue in my 2013 C2S but only one fan would have the behavior you described. Was still under CPO and brought it to the dealer to diagnose. They found a pebble stuck in the fan and removed it...quick 15 minute job and I did not even have to leave the car with them. That resolved the issue and it did not reappear.

_RS_

Somewhat related - mine recently kicked up a gazillion codes which "seem" to be fixed with a new battery. One symptom was one engine cooling fan would come on for a few minutes after closing a door or the frunk.
It was like ghosts in the machine.

noddy981

Both my fans operate at low speed with the aircon switched on, but thanks for the suggestion.

noddy981

It might be my car has ghosts too. The battery will be on my list of suspects. Thanks

noddy981

Transpires there were a defective batch of fans fitted to 2016 Boxsters, Caymans and 911s. No recall and no service bulletin have been issued by Porsche. Would be covered under factory warranty but will be down to customer after the warranty expires. Dealers and Porsche specialists were unable to diagnose from the often random and multitude of electrical faults that result in the malfunction of the fan and it took phone call to Germany by a specialist resulting in the symptoms being diagnosed immediately by factory technician. This all proved very expensive for me and should have at least have had a service bulletin issued to assist dealers. Replacement fans need to be ordered to a superseded part number.

LSR

My fan problem is resolved. It had nothing to do with the fans or the battery. Rather, the cause was a sticky DME relay. Fixing the relay cured the fan problem.

safortner

Hi there... I have read through this discussion as I am having same issue in my 2016 Cayenne GTS. Dealer says I need new shutters and new assembly fan to the cost of $7K BUT will not guarantee this will fix the problem. I showed them this thread and they said the relay is located in the assembly fan and the whole thing must be changed, hence the expense. You seem to know what you are talking about.... is this true and accurate? I really appreciate your help, I have been dealing with this problem intermittently since 2018. NO ONE has been able to diagnose!