Cooling fans come on and stay on

[924nutter]

Hi guys I'm sure there's been a thread about this before but I can't find it. My 1992 944 Turbo cab has just developed a problem with the cooling fans. When the engine is stone cold they are inoperative, but once the engine is up to just its normal operating temperature they come on at full power. Upon turning the ignition off they do not reduce to the slower speed as they used to, and I am sure they would contine to run until the battery was flat. The relay clicks and chatters when the ignition is switched on from cold. Last night I disconnected the battery and took out the relay then reconnected and the fans stayed off ( no surprise there) but when I replaced the relay the fans did not start straight away but did start again on full power after about a minute. I am suspecting the fan control sender in the radiator. Anyone had a similar symptom who knows what the fault is? The car has done 44,000 miles.

 

[david924s]

Radiator temperature switch will be the issue or easiest place to start.

 

[Hairyarse]

Yep agreed, temp switch - had same on my old square dash

 

[944 man]

The relay can stick on series two cars too - Ive had both.

 

[924nutter]

ORIGINAL: 944 man

The relay can stick on series two cars too - Ive had both.

Thanks 944man but I don't think the relay is sticking because if it is removed the fans obviously stop, but when re-inserted it takes possibly 30 secs to a minute before the fans come in again.

 

[944 man]

I thought that it was unlikely from your symptoms John, but I always mention the relay because people frequently overlook it. []



Simon

 

[OLD_ian]

That's what is was when this happened to mine earlier this year.

ian

ORIGINAL: david924s

Radiator temperature switch will be the issue or easiest place to start.

 

[MartinRS2K]

Mine had the same problem and it was the temp sender.

I've also got a new relay here if it is that []

 

[bakerloid]

As the others have said - I would guess radiatior temp switch. Had it on my s2, when they fail they tend to get stuck on. Bit odd that the fans aren't on to start with, I.e. literally all the time. But, I would look there first.

James

 

[944Turbo]

I think the temp switch is cheap and the relay expensive so its not a bad way round to check things, the relay is probably easier to fit though. The AC does alter the fan behaviour, think it makes them run on slow as soon as its on. It needs using more! [] just the sort of fault that develops when spending a long time parked!
Tony

 

[kdp]

The fan never operated on my recently acquired 944 and I found that the previous owner had removed the fuse. When I put it back in the fan ran continuously even without the key in the ignition. I replaced the coolant switch and now all is OK.