89 audi 100, fan problems

The message from jimi snipped-for-privacy@hotmail.com contains these words:

Fan switch is stuck. I can't remember if it has a seperate switch or whether it's done through the tmeprature sender, but look down on the radiator and see if you can find an item with two wires leading to it. Unplug it and the fan should stop.

If that doesn't work, it's probably a stuck relay - have a look at the relay listing panel and see if there's one that does the fan. Tap it a few times to see if it unsticks.

No what does this switch look like? Sorry im not very mechanical. Does it look like a light switch or a toggle switch?

Jimmie

The message from jimi snipped-for-privacy@hotmail.com contains these words:

It won't look like a switch at all. It'll be a fitting on the side of the radiator. In general it'll look something like this...

but of course, they're all different! You should be able to unplug it. If that doesn't stop then fan then start chasing the relay.

The fan thermo switch is located on the back of the radiator just below the lower radiator hose. three wire connection for fan speeds 2 and 3.

Still I would be more inclined to check the relays first. Relays for fan speeds

1 and 2 are located int he main relay / fuse box buy the drivers side hood hinge. Fan speed 3 relay is located in the AUX panel under the dash by the driver's left knee. Large and very difficult to pull due to its large conductors to carry the amperage needed for the fast speed. I would suspect either fan speed 1 or 2 relays to be the more likely culprit.

T> The message

So do you recommend unplugging the switch while the fan is running, or when i have the battery unplugged?

Thank you, Jimmie

The message from Tony contains these words:

If you pull the switch plug first it'll tell you whether the relays are stuck or not.

If you pull the relays first it won't tell you whether they or the switch were stuck 'cos the fan'll go off anyway.

The message from jimi snipped-for-privacy@hotmail.com contains these words:

While it's running if you can reach it without undue hazard.

Because I feel that the relays are the problem I do not see a reason to unplug the switch. The switch is used to activate the relays which then power the fan so unplugging the switch will not have any effect if my theory is right.

I would look to the relays first and you can check them with the battery hooked up.

If you still want to unplug the switch you should disconnect the battery first because it is located within inches of the fan and you do not want to be anywhere near that when it is running.

T> So do you recommend unplugging the switch while the fan is running, or

The message from Tony contains these words:

What will that tell you? If you pull the relay and the fan stops you're no wiser. It could still be the switch, as the fan won't run without the relay it'd have stopped anyway.

If the OP were confident enough they could poke about with a meter but they don't come across as the sort that would do that.

I was guessing that he would replace the relay with a known good one. Still, your point is correct. I would, however, not recommend unplugging the switch with the fan running.

Agree on the second point as well.

T> The message

The message from Tony contains these words:

Ah, you see, I'm part Scottish, so it would never occur to me to buy a new relay until I was sure the old one was shagged!

Ah, I see. I guess that an ohm meter and jumper wires for power to check continuity of the relay would require added expense as well.

I guess pulling the fan thermo switch is the only option at this point. :-)

A simple test lamp (screwdriver type) would only be a few pounds / dollars - - -

I had a similar problem, and it was the switch. Until I got the new one, I left the switch unplugged and switched the aircon on while driving (which activated the fan at low speed).

Christoph