Radiator fans run off and on constantly

[dgjdrummer]

Hey guys, so I tried to ask this in the sticky for the LC/LCR buying guide but got no reply, basically my fans come on as soon as I start the car and run for around 15 seconds at full speed, then go off for a further minute or so then do the same again and this happens the whole time the engine is on.

From the buying guide it says this is due to a fan resistor linked with the climate control system being kaput meaning the fans don't run at a low speed constantly, and run on/off intermittently instead. Is this an easy fix? And what will i need/need to do to resolve this problem?

Cheers for any help guys!

 

[elviscat]

Hi dgjdrummer, did you find a solution to this, I seem to be having a similar issue, radiator fan on full when start the engine goes off after about a 2 minutes, happened twice now. Doesn't happen all the time if i put the air con on I get the speed 1 fans however.

 

[dgjdrummer]

Hey mate, unfortunately not and now mine don't even run at all! My condensor kicks in from time to time but no rad fans whatsoever! Some searching suggests it's a resistor or sensor within the fans that's at fault which could be as simple as replacing that part or as bad as replacing the whole fan set up....

Sorry I can't help any further mate.

 

[elviscat]

I was thinking could this not be the either the Radiator fan switch? anyone had any problems like this with the fan switch?

 

[Muttley]

You're in the FAQ section which most people don't usually scan for queries.

elviscat, your fan problem is probably not related to the thermoswitch, which is a simple thermostatic switch and would either fail constantly-on or off.

Fans on-off-on usually indicates low speed fan failure, almost always because the series resistors in the fans have failed. The fan control module tries to use high speed fans instead. The constant on-off switching can burn out the fan motor, which sounds like it may have happened to you, dgjdrummer.

Have you checked fuse 180 and 164 in the battery-top fusebox?

Standing in front of the car, going from left to right, first the flat metal strip fuses

S177	110A	Alternator
S176	110A	Interior
S164	40A	Radiator Fan
S163	50A	Engine Management
S162	50A	Glow Plug Heater

then the plugin blade fuses are

S180	30A	Radiator Fan
S179	30A	ABS
S178	30A	ABS (pump)

This Elsa page shows how to test the fans from the thermoswitch connector. If the fans work when you short out the connector pins here then the thermoswitch is faulty.


The diagram below shows the connections to the fan control module, which contains relays that switch the fans on and off.

And this one shows a couple of ways you can get around the slow-speed failure without buying new fans.

 

[dgjdrummer]

Muttley does it again!

Thanks for all the info, will get out there and have a look when there's a bit more light and try the bypass as suggested above.

Cheers

Darren.

 

[elviscat]

Cheers Muttley,

Have just checked all fuses are fine, will bridge the connectors when i can get out and get to the plug,

Have just noticed actually (doh) only because i'm always startint the car and didn;t think it might be doing it without the engine running, however just turning the car on, no engine start, both fans come on speed 2 (fastest) so i think it is the thermoswitch to be honest i.e. failing on! what u think?

 

[elviscat]

Hi all,

Thanks for all your help

Fixed, was the thermoswitch buggered,

Something to remember i think is even though it can fail on, i.e. ignition on fans come on etc as above, once the switch has some heated water on it, it can start working again and acts as normal when the car is up to temp and running etc.