How to control when cooling fans come on

[tdskip]

Hi folks - my 924s has a tendency to only kick in the cooling fans when the engine temperature is right near the start of the red zone on the temperature gauge. Is there way to control when the fans kick on so they start working before the temperature gets that close to the red zone, or is thus by design?

Thanks!

[mattdavis11]

There could be two possibilies...

1) The cooling system has air pockets. Bleed it by raising the nose of the car and loosening the 10mm bleed valve located where the upper radiator hose meets the engine.

or 2) the thermo fan switch is toast and needs to be replaced.

Some how I doubt the latter because it does work, albeit not very well, but it might not be the faulty part.

[tdskip]

Hi Matt - sorry for the newbie question but car running while bleeding it, yes?

(ducks for cover)

[VII]

Installing a low temp fan switch and thermostat might also help with cooling.

[Dantilla]

Originally Posted by VII

Installing a low temp fan switch and thermostat might also help with cooling.

+1.

There are aftermarket thermofan switchwes that kick on at cooler temps. They work well.

[bell]

The fans in our cars are 2 speed fans.....slow and fast, both speeds controlled by the same relay, in the relay there is a resistor which controls the slow speed and is bypassed for full speed fans.....
Chances are the relay board has some bad solder joints or the resistor is burned out......
My 924s has the same problem but I haven't dived into it yet to fix it, if I'm stuck in traffic I just run my a/c which kicks the fans on high LOL
With the fans on slow speed it should be enough to keep the temps in check, when they're off there is simply no effective air going through the radiator unless you're going faster than 35mph......

[Grandad#3]

Hello, Take a look at the fan resister in the link below. If yours looks like this replace the burnt wires. Replace the radiator thermo switch below the upper left large hose.

944 Online Forum - The Porsche 944 Forum For The 944 Enthusiast.

Cheers,
Larry

[bell]

Hey good call on those resistors.....I forgot the later ones had those too....

[smokin_944]

VII is correct in his assessment. Thermal switches have different temp values. 823.959.481E is a 65/60 switch, probably the coldest available. The next one is 823.959.481 and it is a 75/70. These switches will bring the fans on much quicker if that is what you want.

[ernie9944]

Originally Posted by smokin_944

VII is correct in his assessment. Thermal switches have different temp values. 823.959.481E is a 65/60 switch, probably the coldest available. The next one is 823.959.481 and it is a 75/70. These switches will bring the fans on much quicker if that is what you want.

I've use the 75/70 thermo fan switch for years & had good result don't forget to match the rigth temp thermostat to it & replace the so often forgotten rad cap by a new one .

[smokin_944]

Absolutely right Ernie!! The 65/60 keeps the temp too low for the car to get excellent gas mileage... Where I live, the 75/70 is best...

[tdskip]

Great info guys - thank you very much.

So it looks like the following is what I should order from Pelican;

823-959-481-F-75-M2

Any down side to using that in SoCal? She is a quasi daily drive, no track time planned. (for now anyway - grin).

The switch looks pretty simply to install - any tips or tricks to be aware of?

Also - would it be good practice to replace the radiator cap as a matter of course. Pretty sure she has the oirginal one still. Is the correct replacement;

944-106-257-00-M6?

Thanks guys!

[smokin_944]

Yup, remember that you are threading the switch into a plastic tank. Use a torque wrench set at the proper lb to ensure a safe install. Do not overtorque.

[mattdavis11]

I use one wrap of teflon tape on the threads.

[ernie9944]

They shouldn't be any down side using that in SoCal & yes do replace the rad cap you got the rigth part # for an 87-88 924S Cheers & happy wrenching

[tdskip]

Thank you VERY much guys - appreciate the coaching.