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Radiator fan switch or relay?

vincematthews

vincematthews

Member
Just thought I'd run this past you guys as I'm sure there is someone with experience of this.

I discovered the radiator cooling fan has been running (even when the engine is cold) all the time on my '87 2.5 oval dash and running the battery down.
If I put the key in the ignition, the fan goes then goes to high speed.

I've had a look on Clarkes fault finder, but the circuits don't match what I have fitted.
The nearest is the Late Model case, but with just a single 2 speed fan fitted and a large relay 944.615.105.02 with only half the contacts that they show.

I've pulled the relay and the 30M1 to V1 and the 30M1 to M1 contacts are both open which I think is normal?
After refitting the relay, I've pulled off one wire from the rad mounted switch and the fan doesn't run.

Does this definitely mean its the rad switch that is faulty?
If so, is it easy to replace without airlocking problems in the cooling system?

Cheers

 
Sounds like it is the rad switch, same problem I had on my square dash. Easy replacement as long as you don't push your spanner against the top hose spigot like I did, cracking the radiator tank - oops!
 
yep i had this same problem only 2 weeks ago, fitted a new rad switch & all has been well ever since, check before buying that yours is either a 2 pin or 3 pin switch, mine was a 2 pin, but the parts catalogue listed mine as a 3 for some strange reason ? also make sure you have the correct spanner size for the switch, its a big bugger, around 30mm i think. You can do it without losing too much coolant, just make sure the coolant is stone cold first & make sure you have the new switch to hand.... not like i did LOL !!, good luck, oh & dont go paying fortunes from Porsche for one, they list them for about £25, got mine from a good car spares place for £12 inc VAT. Tony
 
or you could just do as I did and pull the fan fuse [;)]
I ran my Lux like that for nearly a year and never had an overheating problem. In fact the only time the gauge even approached half way was when I was stuck occasionally in a traffic jam when I'd pull over and re-fit the fan fuse until I got home.
Might give you some breathing space until you can get the job done. just keep an eye on the gauge.[;)]
 

ORIGINAL: Jinxy

yep i had this same problem only 2 weeks ago, fitted a new rad switch & all has been well ever since, check before buying that yours is either a 2 pin or 3 pin switch, mine was a 2 pin, but the parts catalogue listed mine as a 3 for some strange reason ? also make sure you have the correct spanner size for the switch, its a big bugger, around 30mm i think. You can do it without losing too much coolant, just make sure the coolant is stone cold first & make sure you have the new switch to hand.... not like i did LOL !!, good luck, oh & dont go paying fortunes from Porsche for one, they list them for about £25, got mine from a good car spares place for £12 inc VAT. Tony
Click to expand...

welcome jinxy ..

a good point about sourcing the switch . German Swedish & French (GSF)should probably have one too.
 
Id always replace the switch as it isnt expensive. Failing that the relay, and I have had a relay fail leaving the fan running on a series two car.

I have also run for months with the fuse in the ashtray (when the switch wouldnt come out)!
 
ORIGINAL: peanut


ORIGINAL: Jinxy

yep i had this same problem only 2 weeks ago, fitted a new rad switch & all has been well ever since, check before buying that yours is either a 2 pin or 3 pin switch, mine was a 2 pin, but the parts catalogue listed mine as a 3 for some strange reason ? also make sure you have the correct spanner size for the switch, its a big bugger, around 30mm i think. You can do it without losing too much coolant, just make sure the coolant is stone cold first & make sure you have the new switch to hand.... not like i did LOL !!, good luck, oh & dont go paying fortunes from Porsche for one, they list them for about £25, got mine from a good car spares place for £12 inc VAT. Tony
Click to expand...

welcome jinxy ..

a good point about sourcing the switch . German Swedish & French (GSF)should probably have one too.
Click to expand...
Thanks Peanut, i dont know a lot about these cars just yet, but what i do know i like to pass on [:)], cheers, Jinxy
 
Thank guys

Interesting points.

Put a meter across the switch contacts and got open circuit so I thought must be the relay . . .

Pulled the relay and took the can off to look inside.
Some evidence of a couple of solder points overheating/or resoldered but nothing obviously wrong.
Tried applying power to get the relays to switch and they didn't seem to want to so thought definitely the relay.
Rang OPC and they said £178 so I thought b*$$%r lets double check this.

And when I did, it has surprisingly started to behave like it should and the fan now goes off.

So I've now bought a new switch from Bert Gear - excellent service as usual - as I reckon a 'sometimes works, sometimes doesn't' means its more likely to be the switch than the relay - time will tell.

BTW the AF measurement is 29mm and the thread is M22 x 1.5 - this is on a 944.606.481.00 two connector switch.
 
so I've a quick question on the relay - mine is faulty (fan sometimes stays on for ages, basically until i tap/shake the relay).

Should both fans (944 S2) come on together or is it normal for just one? I wonder if I have another problem as well :)

H
 
yep totally agree, if in doubt always replace. Yeah i think your right it is a 29mm, but for some strange reason i had trouble getting hold of a 29mm socket so opted for the more readily available 30mm instead & it still did the job. Right !... dont tell everyone, but the sun is shining, so gonna do some bits & pieces on the 944 LOL !!, Jinxy
 
From what i know, ( which isnt a lot yet LOL !! ) the slow speed fan only comes on when the engine is off, when the engine is running the high speed fan spools up.... someone is bound to correct me though [:D], Jinxy
 
ORIGINAL: Hairyarse

Sounds like it is the rad switch, same problem I had on my square dash. Easy replacement as long as you don't push your spanner against the top hose spigot like I did, cracking the radiator tank - oops!
Click to expand...


Finally got round to changing that temp. switch. I thought I was going in from the top by removing the airbox but, thanks to Porsche design, one of the bolts is virtually inaccessible.
Gave up and took the sump guard and the rad. fan off for access - much easier though you can end up getting wet. I used an adjustable as the fitting was too tall for the socket I had - only lost about a pint of coolant before getting the new switch screwed in. Topped it up and I think I've got away without having to bleed the system . . . . hopefully.

BTW - the twin fan relay will fit and work on a single fan vehicle.
 
ORIGINAL: Jinxy

From what i know, ( which isnt a lot yet LOL !! ) the slow speed fan only comes on when the engine is off, when the engine is running the high speed fan spools up.... someone is bound to correct me though [:D], Jinxy
Click to expand...


hey jinxy how did you get on with sorting the fan issue ?
The fan works on slow speed with the ignition off and high speed with the ignition on, provided the temperature sensor switch in the radiator senses coolant heat and earths the fan

i've put a bit of an explanation of how they work on this thread which might be helpful
http://www.porscheclubgbforum.com/tm.asp?m=703130&mpage=1&key=򫶍

You're welcome to pm me if I can be of any help with schematics and faultfinding
 
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