Fan Relay Next?

[the_dr38]

So my fan wont go off at all again, the guy at Porsche said try replacing the brand new 3 pin temp sensor with a brand new 2-pin, Im not convinced as this switch worked for a couple of days and was fine. However he said you could try the Fan Relay but it's 140 quid + VAT, the 1985 ones Ive found for a measley 9 quid online, surely you can get them cheaper. Also my relay only has 6 pins and the one he said about had 11, I see that the board could accomodate an 11 pin, is this just a mkii?

Regards

Lloyd

 

[sawood12]

Why would your brand new 3-pin replacement thermoswitch not work where a 2 pin one might? Sometimes electrical items do boil down to process of elemination with replacing parts, but I would think twice about replecing the three pin thermoswitch for a two pin one unitl your very last step. You should be able to test if your relay has stuck permanently on quite easily with a multi-meter.

 

[billus99]

my fan has just started to stay on, but intermittently - flickers on and off, even when cold, but mostly is on. Accompanied by a "clicking" from behind the glove box area. Same problem?

 

[Peter Empson]

I need to sort the same problem out on my 944S, it resulted in a flat battery last week [] I'll definately try replacing the switch first (had one go on my white car a few years back) as they seem fairly common. If that doesn't work I'd try a used relay before buying one at that sort of price!

 

[zcacogp]

Stupid Q here, but how complex is the system? As in, surely the relay could be tested by applying the right voltage to it and seeing whether it opens (or closes.)

With a relay that price, I'd be thinking about redesigning the system to use cheaper parts.


Oli.

 

[Neil Haughey]

Easy to test the thermoswitch thing in the radiator, can't recall how but I am sure the workshop manual has something on this as I can recall testing it on my S2 about 7 years ago. ISTR mine was dodgy so I replaced it.

 

[the_dr38]

ORIGINAL: billus99

my fan has just started to stay on, but intermittently - flickers on and off, even when cold, but mostly is on. Accompanied by a "clicking" from behind the glove box area. Same problem?

Yep, the other day mine did this for the first time in a car park. Every time I went to open the bonnet to remove the fuse the fan went off so i locked the car and walked away and it came on again, 3 times much to my giflfriends amusement.

I just feel like I have wasted my time trying this 3 pin switch because I cannot rule the switch out. But again if it's fitted by me i.e not a mechanic can I still not rule it out?

Lloyd

 

[billus99]

I've still got the problem, have just printed off destructions from Clarks Garage to test the system.
However, there is the "thermofan switch" - which I guess is on the radiator from Mr Clakrs description abnd picture, and the "fan relay" - where is that?

I'll run the tests tomorrow and find out which bit seems at fault, but any advice gratefully received!

 

[billus99]

have just done the tests, appears the fan relay is fine, but the thermoswitch faulty. doesnt look the easiest place to get to, to replace it!

At least the problem only occurs with the ignition swtiched on, so i dont suffer from battery going flat. any ideas best place to get a replacement?

did at the same time fit the new centre console (replaces cassette tray with cubby hole / drink can holder) a lot more useful!

 

[ukmastiff]

I just re read your post , I have a habit of skimming them which is bad. If the fault only occurs when the ignition is switched on it can't be just the thermo switch can it.
The system is wired so that voltage goes to the fans regardless of ignition being on and the fans run after you have turned it off and locked up your car ? or am I missing the point ( it has been known lol)

Best of Luck

Mas

 

[billus99]

Good point Mas, although a receipt in the "History" file tells me some "bodging" may have been carried out in the past, and in my experience the fan has always stopped with igniton.

I've just rechecked it, the fan definitely turns "off" with igntion.

Having said that, if I do the test on the 3 pin plug from the thermoswitch (bridge across terminal 2 & 3), the fan operates - even with the igniton off. However the "intermittent" running of the fan only occurs with igntion on.

Anyone got any other ideas!? any advice gratefully received!

 

[ukmastiff]

I have just realised that I'm talking about a turbo and yours s an s2 isnt it ? . The fans on the Turbo are defo designed to stay on adter the ignition is off due to the very high temperatures involved but why did I have your car as being a turbo in my head ? lack of attention and old age is the only pathetic excuse I can offer for an incorrect post.

Soz

 

[billus99]

No worries - yes, its an S2, not a turbo.
Thanks anyway, your advice has at least made me double check, and confirm that the problem only occurs with igintion on, even though shorting thermoswitch plug makes fans operate with ignition on or off.
Having done that, I thought "s0d it", put the bits back together and went for a blast around the countryside for an hour, roof down - now I feel MUCH better about owning it, even thuogh theres a new problem to fix!!

 

[pegasus]

Hi there,just to clear things up the fans are powered at slow speed when the ignition is off for a time after running the engine to remove latent heat from the engine(the stopping of the engine stops the forced circulation of coolent and for a short time the water temp will rise slightly) when you tested the three pin fan switch you would have proved that the fans run at slow speed bridging the correct two terminals with the ignition off and that the fans run at fast speed when bridging the correct two terminals with the ignition on. If the problem you have is the fans running at high speed and swithing off with the ignition this is a faulty switch and not a wiring problem. As for removong the said switch you need a hex deep socket that is specifically made for the job,27 mm I think, i may be mistaken,very cheap to buy, hope this helps.

 

[billus99]

thanks
No, the problem is that the fans keep switching on and off (sometimes every few seconds), even when the car is cold, as long as the igntion is on.
It's noticable when stopping the car, as in normal running you wouldn't exepct the fan to be on, unless you have just been thrashing it. And, it isn't constantly on, it keeps going on and off. This only happens when th ignition is on. And, it does it when the car is first started, even though its obviously completely cold.

 

[944Turbo]

If you have AC I think this complicates issues as when the AC is pressed I believe one fan runs on slow all the time the AC is on. So If you have AC and its on the fans should run, if not they should only run when the switch in the rad kicks in and that should be with ignition off or on.
I don't know the exact operation of high and low speed or where the AC side is integrated - at the relay or elsewhere.
Tony

 

[billus99]

New thermo switch solved the problem (fitted by Promax, thanks guys)
Couldnt put it back in the garage, tho, so have been tanking up and down the motorway to birmingham and back - more "road testing"!
same again tomorrow (unless theres loads of snow...)

 

[peanut]

ORIGINAL: billus99

have just done the tests, appears the fan relay is fine, but the thermoswitch faulty. doesnt look the easiest place to get to, to replace it!

At least the problem only occurs with the ignition swtiched on, so i dont suffer from battery going flat. any ideas best place to get a replacement?

did at the same time fit the new centre console (replaces cassette tray with cubby hole / drink can holder) a lot more useful!

if the fan only comes on with the ignition switch you have a problem. This cooling system is designed to work after you switch the engine off as well as when the engine is running. The engine temperature soars several degrees after you switch off .
The fans should run independantly of the ignition switch and should be constantly live. This will prevent you blowing your head gasket when coolant isn't being circulated.
Sounds like the power supply to the fans, switch and relay have been re-routed due to a previous problem which caused a flat battery.

 

[billus99]

thx, but in fact now the fan does continue once engine / ignition swtiched off.

However, I don't really think that blowing the fan makes a big diference once engine swtiched off, as the water isn't circulating anyway....

c'mon, lets argue this one! don't let the thread get relegated to page 7 obscurity!!

 

[pegasus]

Hi there, even though there is no forced circulation when the engine is stopped you still get a small thermo syphon cooling effect and the air being blown at the engine probaby helps cool things down, I don't know how by how much but it must be better that not having the fan run,after all it must cool the water in the top of the radiator to make the thermo switch turn off, all the best John.