Thermo Fans running at full tilt

[The_Hawk]

Any electrical engineers in the house??

After getting my air con fixed, which as it turns out was a matter of plugging a plug in properly the thermo fans now run @ 100% when the car is on. When you switch off they drop to low speed for a few minutes.

Now I have never noticed the fans on before, so it's likely that the plug that wasn't in right also controls the fan. But then the temps sit dead on 90 so they were probably never needed anyway.

The water temp still seems to get up to 85 - 90 anyway, although I would say it's now slightly lower with the fans on. That and it's damn noisy outside the car and the buzz of the fans can be heard inside too.


Loon has suggested that maybe the temp sensor in the radiator is stuffed and being a cheap enough part it's worth a bash to swap it out for a new one in the hope that solves the problem.
The question is, is the temp reported in the car drawn from this same sensor? That being the case, wouldn't that suggest it is working correctly?

The quick and nasty option is to drop in a toggle switch so I can manually turn the fan off when it's not needed, although the danger being that you then need to be aware when it needs to be on.

Anyone ever have a similar issue to this?

[DubSteve]

Yeap its usually noisy after you have just fanged it or stuck in traffic your not moving anywhere and basically your sucking in hot air its normal, nothing to worry about

[The_Hawk]

Yeap its usually noisy after you have just fanged it or stuck in traffic your not moving anywhere and basically your sucking in hot air its normal, nothing to worry about

Thanks for the response, but these fans are ALWAYS on 100% from the moment you start up to the moment you stop, regardless of how you drive. Seems the thermo part isn't adjusting power as it should.

So either the temp sensor is playing up, which seems odd since the gauges all read right, or the fan speed control unit. Golf Loon swapped out (what I'm sure is) the speed control unit and that didn't help, which leaves the temp sensor.

[DubSteve]

I would say maybe a sensor is fried or something along those lines.

[static1800]

this may seem silly but, you don't have your AC on all the time do you? Because as soon as you do the thermo will come on.

[The_Hawk]

It's not that silly... GolfLoon thought that may be the case, and it was tested with both the original and replacement part and it had nil effect with the AC on or off.

You have widened my thinking on the possible problems though, maybe it thinks the AC is on when it's not...

This sound like it's going to be a fun problem That manual toggle switch is looking like it may end up being the way around this.... still there is a few things to be investigated first.

[The_Hawk]

The car went into McGrath VW @ Liverpool today to have a spare key coded and they mentioned the thermo fans.

I had asked for a price on a new temp sensor ($80) but the guy said he doesn't think that is the cause of the problem. He seems to think it's a fault in the fans themselves, but wants to run more diagnostics to see. He nicely provided a price for replacements fans too... $1800

We will see how things go, but that manual toggle switch is sounding better and better everyday...

[joshyd-mk2gti]

Loon has suggested that maybe the temp sensor in the radiator is stuffed and being a cheap enough part it's worth a bash to swap it out for a new one in the hope that solves the problem.

this is the first thing id be doing. that guy quoted you $80..? should be heaps cheaper than that. put it in your self too, its easy as, if your quick enough you wont lose much coolant.

http://www.germanautoparts.com/Volkswagen/Golf/Climate/181/2

edit: does the vr6 have one of these? http://www.germanautoparts.com/Volks.../Cooling/336/2 have a look under the coolant tank. coolant may have spilt onto it somehow and shorted it out, check the fuse in it.

[Golf Loon]

There are 2 sensors mate.
The one on the thermostat housing on the engine controls the instruments and ecu and could cost $80

The one on the radiator is heaps cheaper and controls the fans. Go there first.

[The_Hawk]

That sounds like the go Golf Loon, I didn't realise there was two different sensors.

Will have to have a look at the parts place tomorrow for a few bits and pieces...

joshyd-mk2gti: Yes it has one of those and swapping it out for an alternative has no impact, so for the moment I assume it's working fine.

[The_Hawk]

joshyd-mk2gti: That was the wrong sensor and Golf Loon, sadly McGrath charge $78 for the other one

Oh well, I have it now and will install it thisafternoon and see what happens.

*crossed fingers*

[99gti]

Thermo fans are buggers of things. Good luck with it, it'll be interesting to see how you go.

[The_Hawk]

Plugged the sensor in without installing it, so it should be reporting ambient and not turn the fans on at all, but sadly no, still does the same thing.

So new sensor failed, replacement speed control module failed, mind you none of these parts were properly installed, simply plugged in inplace of the originals. Maybe the bolt will make the difference !!!

Maybe a combo of both new parts should be tried at once...

Maybe it's the fan itself?

Maybe I should just give up and get the toggle switch.


... I wonder if McGrath will allow me to return the unsed part, especially considering I haven't done anything with it and it cam in no packaging, so I can return it in exactly the same condition I received it

[The_Hawk]

Well the problem is now soved quite nicely. The auto elec has put a switch in for me that controls just the high speed part of the fans. This means it should still work at low speed when it needs to, but high speed is controlled by the switch.

Just have to remember to turn it on when I turn the aircon on (or when it gets hot )

At least it's much quieter now.