tony944

Hello,

I have a 944 S2 1990 Cabriolet and am experiencing some problems with the cooling fans. When the engine has been running for a few minutes, the cooling fans kick in as they should when the engine reaches a certain temperature. These fans then shut off about one minute later, and then activate again, and then almost immediately switch off and then on again. The fans then remain on indefinately, until the car is turned off. If the car is turned on when it is already hot, the fans turn on immediately, but again, they do not turn off at all then until the car is turned off. I have replaced the cooling fan relay, however this has not resolved the problem. What else could be causing the fans to remain on?

Thanks, Tony

joonas

http://www.clarks-garage.com/shop-manual/cool-01.htm

xsboost90

sounds like the coolant temp switch on the ds of the radiator- pretty easy to install. Eventually they will just stay on all the time, even when the car is off.

black944inMO

Could be air in the system. might want to bleed it to make sure.

bearone

the temp switch fails, running all the time or not at all, not a bleeding issue.

87951

GOBOGIE

For the most part yes this is true!

black944inMO

That is correct. for the most part it can be. Which is why I said it could be air in the system. For one it doesn't hurt anything to bleed the cooling system. it's messy, but easy to do. 2nd, it can be air with the symptoms he described. turning on, then off then on, could be an air pocket trapped and moving around in the radiator.

this is something that doesn't cost anything to try and takes less then a half hour. Is it most likely the problem? No. It's most likely the temp sensor. But again, that's why i said it COULD be air. let's give the guy a few options to check.

GOBOGIE

You raise an interesting question albeit! Others are definitely more knowledgeable about this than me, but won't the (possibility of) air in the system just cause a general lack of "cooling" and not necessarily the switch turning on and off? Wouldn't it just cause "overheating" issues?

Granted I've had almost the exact same problems as the original poster and it was indeed the switch (I think under $30) on both the '86 944 and the '89 951 I've owned.

I'm asking, not telling!

black944inMO

Think about it this way.

Get a bowl. imagine a sensor sticking about 1" from the top. Fill the bowl till it is 1/2" above the sensor. Now move the bowl back & forth. The water isn't always touching the sensor right? Now boil the bowl. Which is hotter the water or the air above it? Pretty simplified way to look at it, but same principal.

I'm still with everyone above that it's the sensor. But just like everything else on these cars, sometimes the obvious isn't always the problem. And what's the harm in bleeding the system or even doing a flush/fill? Doesn't hurt anything so why not at least try it.

GOBOGIE

OK - Makes sense now! Sorry I'm a PT not a mechanic... I just don't think mechanically! See me for back pain though ;-)

black944inMO

No problem. I'm no pmechanic either, but I play one on the net. will be going through Indy in the next week, might need to take you up on that back pain. hahahaha

pjburges

He mentioned 'fans' - so both fans are cycling on and off? The A/C fan can be triggered seperate from the main coolant fan (at least thats how my 87 is wired). Before you replace the sensor you should verify that your coolant fan relay is working correctly. It is a 2X 25Amp relay and is one of the most stressed in the car...