any idea's? I drove the car for most of the day and did notice the temp being out of the normal range. Thanks.

 

the relay for the electric fan can fail causing 2 situations:

-Radiator fan stays on until the battery dies

-Radiator fan stays off until your car blows up

sorry.....check your radiator fan relay and fuse. Test the fuse first. Usually a dead fuse will result in a fan failure.

BTW, do you have a low temp fan switch? I have like a 93/88 degrees celsius? that could cause the fans to stay on for a while. I have that fan switch and my fans stay on for a while, but at least the engine stays cool (a little below 1/3 hash mark on 85.5+ cars)

 

Don't be surprised if it is the fan switch itself that has failed, and not the relay!

 

Pull the - lead off the battery before the current draw kills it. I learned the hard way very recently that that stupid $10 coolant temperature switch can easily cost you a $120 battery!

 

Thermoswitch on the radiator, no doubt.

If you decide to replace the switch with a lower temperature unit, you should also fit a thermostat with a matching temperature rating.

 

I had the same problem of fans staying on. It was the thermostat. As a temporary fix, pull the fuse when you park up. (Let it run for a while first)
A replacement is fairly cheap and you can do it yourself. You need to drain the coolant first. The only difficult bit is to get a tool into the confined space to undo the thermostat. Mines an S2. Had to take off the air flow meter to get to it.
This is the culprit.

 

This is the thermoswitch. Thermostat is in the waterpump.

You are correct, brain and fingers not engaged.

 

Thank you all for your help. sounds like its a easy type of fix, my favorite type. will check it out today.

 

crap I just realized I said relay up there WTF was I drinking that night? Fan switch too.

 

I believe there IS a relay associated with this system also, but chances are it's the thermoswitch and not the relay. Obviously if you change the switch and the fan still runs continuously, you'll have to consider the relay also. I've heard of the switches failing with some regularity; by the same token, I've never heard of just the relay failing.

 

It must be easy to check the thermo switch. Just look for no continuity when it's cold, right?

 

I believe that is correct, although depending on make / model it might be a bit tricky to get test leads onto. When I get my new one I'll test your theory - it'll be a good thing to know / post. Thanks for the idea.

 

You can test the thermo-switch by simply unplugging one of the wires from it (by the drivers side of the radiator). If the fans stop that is the problem, so leave it unplugged and just use your a/c **** to turn the radiator fans on as necessary.

I had to change mine and the first replacement I got was a low-temp one, which caused the fans to stay on as soon as the engine got slightly warm not even to the first mark on the gauge and then would not switch off (since i didn't have a low-temp thermostat i think) - so i put in a regular temp switch and it was all back to normal.

If you are quick pulling the old switch and putting the new one in you may get a bit wet, but you shouldn't need to drain the coolant.

 

I've had the thermoswitch fail with identical symptoms to those indicated in this thread.

I've also had the relay fail, only it was in a very hot climate and the coolingsystem was under a lot of stress. One day I heard a loud crackling sound from the fuse box (on early cars it's under the dashboard) and the cooling system started behaving erratically.

I don't think this happens nearly as often as the thermoswitch going bad, though.

 

I had this happen to me a few months ago. Really easy to fix and diagnose. Luckily my friend Randy_J lived nearby and had a spare fan relay, so i just switched them out when the fan was running after I shut it off.
Having crossed my fingers, then fan stayed on with the other relay, so it was just the $20 fan switch and not the $??? Porsche relay.
You dont have to drain the system, just unscrew it and pull it out quickly and put in the new one.
There are other threads on this; some people say you can reach in through the top and do it; I cant see how thats possible. I went from underneath and pulled out the fan assembly. Its alot easier this way, and really doesnt take that long.

PS fix it soon to avoid any further draining of your battery!