The Project Pad

Hello everyone,
How long should my fan run after my 92 UrS4 is shut off? I don't remember my fan running very long last summer, maybe 5 minutes. Yesterday my car battery was dead and had to jump her and I think it's from the fan running too long. Today I noticed it ran for a good 10 minutes after my car was shut off and it's only 60 out side and my temperature is running well within normal operating temp so I don't think it should run as long.

Second question on this would be what module and part number would I need to replace if my module is starting to go bad?

Thanks again for the help guys!

When that happens, pull the connector off the Thermo Fan Switch and see if it turns off. (big round sensor in bottom DS radiator 3 pin) If it goes off your TFS is bad. If it stays on, your fan relay is likely sticking, and bad.

Thank you! I'll give it a try.

I had same issue and it was the relay

I've lost a car to that relay (my best guess anyway of where the fire started)

I haven't had a lot of time lately to check this but for now I'm thinking it's my relay so I wanted to see if you guys would agree...

Yesterday I had to move my car over about a foot so my wife could get out of the garage (I was in the drive way). I started my car, backed up, pulled forward out of her way. The car was on for less than 1 minute and was cold when I started it. When I turned her off the temp needle hadn't moved at all but the after run fan came on still for about 5 minutes.

So that to me sounds like the relay, would you all agree?

You can guess or you can test it like I said, its your car... knowing for sure what the problem is > shotgun diagnostics, but if you're asking for opinions it sounds more like the thermo fan switch to me. Relays don't spontaneously turn on without a signal, but can stick on after the fact. Its a simple task, next time you notice the fan on when its not supposed to be, yank the connector off the TFS. if it goes off, there is your problem. It cant be any more simple than that.

If you would rather throw parts at it, replace both.

Per http://www.sjmautotechnik.com/trouble_s ... mfsns.html I found the after-run temp sensor (the 2 pin) and so I ran my little test (thanks again Scubadave)...

I turned the car over, let it run for under 1 minute and then turned her off. The fan started up so I pulled one of the pins off and the fan stopped.

My next question is, can I leave it unplugged till I receive my replacement sensor (going to order it this week) or should I leave it plugged in and let my car run for 10+ minutes every time I drive it (even if it has to sit idle) so the battery charges up all the way?

Thanks again!

Last question on this for me (hopefully)...

What's the part number of the Thermal Fan Switch? I've been looking for the part number and all I can find with my searches is "F98 Thermal Switch" which I can't find anywhere to purchase.

Thanks everyone again.

054919369B but there's a good chance the 324 relay/control unit is at fault too. Does the fan turn off eventually or does it keep running until the battery dies?

The fan turns on right away, as soon as the car is off. Then I've only noticed it run once past 10 minutes but I've not checked it more than that. I've just noticed it come on when I turned on my car for less then a minute (temp needle was pegged at cold) when it was sitting for 4+ hours (it was cold). But I've had to jump my car twice since then as well.

So I know for sure that the thermal fan switch is bad.
I think my battery is getting weak.
Possibly have a bad relay as well.

My plan is to replace the thermal fan switch now and actually monitor how long it stays on with the new switch. If it runs longer than 10 minutes I'll get a new relay as well. Then soon (as in a month or 2) replace the battery before it starts getting cold out.

And BTW, Austin you are awesome. Thanks again!