Need help with my car (90 Mercury Sable)---fan problem

daveleau · December 31st, 2002, 06:29 PM

Hello,
I have a 90 Mercury Sable with a 3.0L engine, automatic trans w/ air.

The fan will not come on and the car will overheat. When it is cold outside, as long as I don't sit in one place and idle, the car is fine (cold air rushes through the engine...). When it is hot outside, the car just overheats. I noticed a loud fan noise for about 2 weeks before this happened. It stopped, and the car began running hot. This led me to believe it was the fan motor, but the fan motor checks out fine when wired directly to the battery.

Things I have done so far:
--Pulled fan and motor for testing--result: fan spun easily and motor kicked on when wired directly to the battery
--replaced fan relay--result: no change

Thanks for any help.
Dave

PS- anyone know of a good car forum???

Richard Cranium · December 31st, 2002, 06:35 PM

I had a Honda come in with that symptom, turned out to be a loose plug on one of the connections.

Use a Voltmeter to trace the voltage, you may have to induce voltage into the circuit as the temp switch will not be closed until the proper temperature is reached.

you mentioned "relay"
In addition to this, you have a temp switch which is usually located on the passenger side of the radiator.

daveleau · December 31st, 2002, 06:40 PM

Thanks. How hard is the temp switch to get to? It is only $13 at my local store, so I think I'll give it a shot too.

daveleau · December 31st, 2002, 06:41 PM

Also, will pulling the temp switch drain my radiator?

SPEEDO · December 31st, 2002, 06:58 PM

My Tempo, Ha Ha, has a sending unit on the head next to the gooseneck for the radiator hose. These have been known to get broken wires where they go into the sending unit and cause the fan not to work.

Try to follow the wires back from the fan to see where they wind up. Then when the motor heats up wiggle the wires and see if it comes on. Better yet just pull the connector off and jump across the pins in the plastic connector with the ignition switch on.

willy_ph · December 31st, 2002, 07:01 PM

My parents had the same problem with their Taurus (94 GL Wagon). I'll ask them what needed to be done to their car.

larrwhit · December 31st, 2002, 07:31 PM

just wire the fan so it comes on with the ignition switch (like the radio for example) and let it run all the time

Epyon9283 · December 31st, 2002, 07:42 PM

I have the same problem on my '94 Cavalier. I really need to get it fixed soon before winter is over...

uethello · December 31st, 2002, 08:04 PM

You have a sensor, a fuse,a relay, a motor, the wiring.

Check the fuses.

Take a long piece of wire, run it from the positive battery terminal to the hot side of the fan, if it comes on, the fan itself is good.

Get a Haynes to find out where the relay is on this car, maybe with the fuses, maybe not.

If all this checks out, try checking the continuity on the wires,

If all that's good, replace the sensor.

9 out of 10, it's the fuse or relay.

edit > doh! read all the post, then reply. I'll leave like it is, maybe it'll help someone else

Go to Cafe Dartre over at cartalk.com link>> cartalk.cars.com

originel · December 31st, 2002, 08:14 PM

yeah, i would also say it's the relay or the fuse.

do you have a chilton or a hanes manual for your car? (if not i would highley recommend getting one). in the back there are wiring diagrams of all teh electrical systems in your car. all you do then is see what components there are in teh system and test them all, and if you still don't find it then it means you have a loose connection somewhere. also if you don't have a multimeter i would also recommend getting one. that way you can check and see if you are getting any voltage to the components when they're supposed to.