Overheating Fan not working

[Rorycaws]

I have just bought my first saab a 9000 CSE 1994 from my parents. They have had a problem for a while with the engine running very hot, the only way to keep it under control is to keep the air con switched on constantly, as this seems to run the cooling fan as well. the fan thermoswitch has been changed but made no difference. any ideas?

[wrighar]

Check the pins in the connector plug for the blue wire from the the radiator temp sensor.

The plug resides right down low and can just be reached throught the towing eye hole and also down under the drivers side headlight.

Mine was corroded to pieces and several other have had blue wire problems.

Andrew

[trollbooster]

Several possibilities here,
Firstly, the fan is stuck. The fan - without wishing to state the obvious!- sits at the front of the car, experiences everything the road throws at it, water, salt, mud etc and the extremes of temperature. Sometimes all this crud and damp induces enough corrosion to prevent the fan from spinning. Often it is enough just to spin it by hand to get it away. Watch out that you haven't left the ignition on or the engine is hot when you try to free it off!!!

Keeping your fingers clear, undo the connector and apply 12 volts direct to the fan, if that works then it's OK. I'm not sure if your car has two fans or not - one for the cooling and another for the A/C - but if just one and it does spin with the A/c on then the above is clearly not the case.
It might be that there is a blockage or airlock in the cooling system and the water is not circulating properly - when the engine is thoroughly hot, is the radiator hot too, near the switch?
It might be that the new switch is U/S (not too likely). Try shorting across the terminals to see if the fan starts. If you know the fan runs with 12V applied your next step is to see if 12V is getting to the fan. Connect a test meter or light to the harness side of the already disconnected fan connector and short out the thermo switch. You should get 12V at the connector.
If shorting the switch doesn't give the required voltage at the fan, then the problem is either relays or wiring. Check all the connectors, clean and tighten them, make sure all the wiring is sound and then check the relays. I'm not sure where they are on your car, but I am sure the handbook will reveal! If they are working, you should be able to hear them click when your 'assistant' shorts out the switch. Of course if they are not working, you won't hear them....
Hope this helps!

[trollbooster]

Originally posted by Scaero (Maptun stg3):
[qb]Check the pins in the connector plug for the blue wire from the the radiator temp sensor.

The plug resides right down low and can just be reached throught the towing eye hole and also down under the drivers side headlight.

Mine was corroded to pieces and several other have had blue wire problems.

Andrew [/qb][/b]

Sounds like Andrew knows exactly what the problem is!! I'd go his route first

[Mark B]

Welcome to Saabscene Ror.

As stated above, you have a break somewhere in the dreaded blue wire or its connectors. You will find a reasonable description of the system in this post.