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Radiator Fan misbehaving

Outrun944

Outrun944

New member
In the last week its started running hot, radiator fan deciding to come on seems intermittent. Although last 2 or 3 tests it hasn't come on at all.

First time it happened, after a short run I got stuck in slow moving traffic on a hill - stopping and pulling off for a couple of miles I noticed it was the needle was in the shaded area ... pulled over and fan was on OK... let it cool down and noticed the coolant expansion tank cap was not exactly 'tight on'. Tightened it ... and for a day or two she behaved herself, last test fan came on and everything cooled. Lovely.

Last night the overheating returned this time the fan wasn't on - and it was in the shaded area. Grr.

So onto today... I had ordered a new expansion tank cap which arrived the day before, so replaced that today and feels a little tighter than the last one.
Just gave it a quick run to warm up - this time after good runs up and down steep hills the temperature was taking much longer to climb (Yay! I thought!) and pulled into my garage when temp gauge was just over the half way point.
Put the heat on full and kept revs at 2500 just to check fan was coming on ... normally comes on at the 3/4 mark (or last mark before shaded area) ... but gah ..... NO FAN NOW!

Given a little bit of history there in case anything may be connected.

But it seems fan isn't coming on.

Is there any way for me to determine if its the fan motor? Dodgy thermostat? Anything else?

Cheers!
 
Any ideas guys? I'm having to drive out shortly, can stop by my garage on the way though.

*edit*

Journey/trip cancelled today. Done another test ... revved it up and allowed it to climb to near the shaded area on temp gauge (square dash model of course) and no life on the radiator fan. I've ordered a new thermostat, they're only £20odd - might as well.

But same question ... any other tests I can do to determine if it is the thermostat, fan motor or something?

Last time I had a thermostat go on the previous 944 the fan stayed on constantly! Quite the opposite!
 
OK been to the mechanic today, didn't have a great deal of time to look at it - he did me a huge favour fitting me in with his work load today ... but no joy sourcing the issue and he's asking me to bring in wiring diagrams (which I've found now).

Ignore what I said about the 'thermostat' - DOH - I meant to say thermo fan switch. But we don't think that's the issue as using a voltage tester we're getting absolutely nothing to the fan (hence him asking me to bring in wiring diagrams to help get this sorted in time for end of Wednesday).

Do you guys have any other ideas what this could be causing the fan to be dead? If we're not getting any power to the motor anyway can't be a dead motor right? And if the thermo fan switch was dead the fan would be constantly on yea?
We did a check of fuses and they all seemed to be ok
 
Does the fan spin by hand or has it seized?
Try connecting the fan motor directly to a live feed from the battery and see if it spins if not then the fan motor is likely to be broken, if it does work then it is the control circuitry for the fan motor
 
Thanks David, we've sorted it now.

First we replaced the thermo/radiator fan switch and checked the circuit which was broken between the relay and coolant fan. Repaired wiring and job done.

For anyone else who comes across this topic needing assistance with wiring with the radiator fan, the diagrams (from the workshop manuals) are online at pelicanparts website. Here's the URL to the image to do with the radiator fan circuit -
http://www.pelicanparts.com/944/electrical/944_84_6_1.jpg


 
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