LCR .. twin fans

Muttley

Catch that diesel!
Mar 17, 2006
4,987
31
North Kent
I realise this is a very late answer, but maybe it'll help somebody.

The radiator fans are triggered by a thermoswitch in the radiator itself. You can remove this and stick it in a saucepan on the stove, with a thermometer, and check that it performs as specified:

1st speed
on: 92...97 °C
off: 84...91°C
2nd speed
on: 99...105 °C
off: 91...98 °C


Both fans should run at low speed when the air cooling compressor is engaged ("snowflake"). This is to pull air through the refrigerant condensor unit, mounted in front of the radiator, all the while the air cooling circuit is active. The original equipment does this by feeding 12V to the fans through a big resistor in each one, which cuts the power delivered to each fan, making them turn slower.

The fan control box under the battery tray combines the signal from the Climatronic unit with the output of the thermoswitch in the radiator. The Nime box replaces that control box, and does away with the resistors that have failed by controlling the power output to the fans using a switched-mode controller.

So if the Nime box makes your fans work when the airconditioning is selected, then it and your fans are working. I'd suspect the thermoswitch in the radiator, or the wiring between radiator and Nime box.
 

mjt

Active Member
Jul 12, 2008
365
1
I swear my fans have never come on, ever.
Altough my compressor is knackered..

pd150 fwiw
 

quattrojim

Guest
I realise this is a very late answer, but maybe it'll help somebody.

The radiator fans are triggered by a thermoswitch in the radiator itself. You can remove this and stick it in a saucepan on the stove, with a thermometer, and check that it performs as specified:

1st speed
on: 92...97 °C
off: 84...91°C
2nd speed
on: 99...105 °C
off: 91...98 °C


Both fans should run at low speed when the air cooling compressor is engaged ("snowflake"). This is to pull air through the refrigerant condensor unit, mounted in front of the radiator, all the while the air cooling circuit is active. The original equipment does this by feeding 12V to the fans through a big resistor in each one, which cuts the power delivered to each fan, making them turn slower.

The fan control box under the battery tray combines the signal from the Climatronic unit with the output of the thermoswitch in the radiator. The Nime box replaces that control box, and does away with the resistors that have failed by controlling the power output to the fans using a switched-mode controller.

So if the Nime box makes your fans work when the airconditioning is selected, then it and your fans are working. I'd suspect the thermoswitch in the radiator, or the wiring between radiator and Nime box.

Thanks for this info! useful to know.

so my fans were pulsing on high speed before, so fixing using the Nimne box has helped as they now both turn when air con is used.

However, by using the Nime fix i have cut the power to the fan control box?
and this is why they wont work when the aircon is off, because the thermoswitch in the raditor is busted?

but the only way to fix that is to buy new fans?
 

Muttley

Catch that diesel!
Mar 17, 2006
4,987
31
North Kent
quattrojim wrote

so my fans were pulsing on high speed before, so fixing using the Nimne box has helped as they now both turn when air con is used.

They should run at low speed when the air conditioning is switched on. If they do, then the fans are OK to work with the Nime box.

However, by using the Nime fix i have cut the power to the fan control box?

The Nime box replaces the OEM fan control box, which should have no connections now and can be removed.

All three input connections that went to the fan control box should now go to the Nime box.

One power output from the Nime box should go to each fan.

and this is why they wont work when the aircon is off, because the thermoswitch in the raditor is busted?

Not necessarily. Look here

RadiatorFancontrol.gif


With the original fan control, the resistors in the fan casings reduce the power to the fan to give slow running. The Nime box bypasses the resistors by controlling the power directly. But you need to plug the thermoswitches into the Nime box as well as the "A/C Compressor On" wire.

but the only way to fix that is to buy new fans?

No. The Nime box is designed so that you can still use the fans even though the resistors have failed.

If your fans are not responding to radiator temperature then possible failures are
1) Thermoswitch broken. Not too likely, both switches would have to fail.
2) Wiring failure between thermoswitch and Nime box.
3) Failure of the Nime box itself. But only partial, as fans still run on "A/C on"

I think it is possible that you haven't connected the thermoswitch to the Nime box properly.
 

quattrojim

Guest
Thanks Muttley thats some great info there! thanks for the help.

Its quite possible i could have wired it up slighty wrong as i did think it kind of worked with the fan control box but now know it replaces it.

i will check the wiring soon and hopefully that will be problem solved!!
 

quattrojim

Guest
quattrojim wrote


All three input connections that went to the fan control box should now go to the Nime box.


i have just read back through this thread and realised i used the guide by Muttly, and did it exacly the same.

although i will double check all my wiring as soon as i get time, should installing this way still allow my fans to come on when the engine is hot?and turn on slow speed when AC is on,

if so is it likely something else could be my problem? sorry for all the questions but seems your very clued up on this subject!
 

rackha

Active Member
May 30, 2007
57
0
west midlands
some help please this may of been covered but need some clarifaction, my fuse for my radiator fan keeps on blowing everytime the fan kicks in so obviously a short somewhere, the fans do work for a second or two before it blows and they are not really noisey so not sure if its my fans that are at fault or this control module that i keep hearing about.

can someone please guide me in right direction and where this module is located if that is the problem.
 

Jonwm

New to the MK2...
Jun 22, 2009
405
0
Tamworth
I'm now slow again!!! :)

On the last day of my warranty I decided to edge my bets at the Local VW Specialist I use with my Fan Fault and as soon as i said the Problems they said it was just the SMALL fan that was the problem not the other, I said its both, described the pulsing and lack of slow speed when the aircon was on, they said deffo only the small one, rang warranty and they accepted the £235 bill.

I let them do it and had no hope that it would fix the problem, but it does!!

So it looks like only the small one needs replacing and at £235 fitted thays not too bad!

Both fire up slowly as soon as I press the "snow flake" and stay on, no pulsing just pretty much silence!

Jon
 
Jan 22, 2007
2,074
0
some may say lala land....
right, having read all 15 pages i need to understand something as i got lost about page 7 or earlier.
still not sure on what is correct or not in terms of "expected normal behaviour"

with engine at tickover -> no fans
with engine at tickover & aircon on -> both fast speed pulse
with engine at tickover & aircon in auto mode -> both fast speed pulse

is this normal? what is?
 
Jan 22, 2007
2,074
0
some may say lala land....
cheers Willie.
That means to me then:

with engine at tickover -> no fans -> CORRECT
with engine at tickover & aircon on -> both fast speed pulse -> WRONG -> should be constant slowspeed
with engine at tickover & aircon in auto mode -> both fast speed pulse -> WRONG -> should be constant slowspeed

is that correct?
and if so i need a fix
 

Jonwm

New to the MK2...
Jun 22, 2009
405
0
Tamworth
cheers Willie.
That means to me then:

with engine at tickover -> no fans -> CORRECT
with engine at tickover & aircon on -> both fast speed pulse -> WRONG -> should be constant slowspeed
with engine at tickover & aircon in auto mode -> both fast speed pulse -> WRONG -> should be constant slowspeed

is that correct?
and if so i need a fix

Yes mate, needs a fix, mine got done today £235

Jon
 

Willie

LCR Track car
Aug 6, 2004
8,939
1
Sunny Scotland
cheers Willie.
That means to me then:

with engine at tickover -> no fans -> CORRECT
with engine at tickover & aircon on -> both fast speed pulse -> WRONG -> should be constant slowspeed
with engine at tickover & aircon in auto mode -> both fast speed pulse -> WRONG -> should be constant slowspeed

is that correct?
and if so i need a fix
Yup

Yes mate, needs a fix, mine got done today £235

Jon
How much were you for the unit and from where?
 
Jan 22, 2007
2,074
0
some may say lala land....
ok thanks.
didn't see a clear easy list of what should be looked out for, and no i know.

arse & pants.
Right, does this nime box actually work now? as i know some have had issues & it has been modified.
 

Willie

LCR Track car
Aug 6, 2004
8,939
1
Sunny Scotland
ok thanks.
didn't see a clear easy list of what should be looked out for, and no i know.

arse & pants.
Right, does this nime box actually work now? as i know some have had issues & it has been modified.
The old one worked for me but I had ABS issues. They have said to send back my old one with £20 and they'll update it. should really do this as its cheaper than the £135 for the unit

The unit was £135 not sure where from as the garage ordered, I think they use gfs, 1.5 hours labour.
Got mine done at Midland VW
Thank you
 

redkite

Active Member
Apr 10, 2005
61
0
oxford
Have you read the Slow Speed Radiator Fan thread that Andypotts1981 started. The mod worked for my LCR and only cost me about £30 in parts.
 

mjt

Active Member
Jul 12, 2008
365
1
My AC doesn't work and the fans don't spin.

I've always thought the compressor was knackered. Coincidence?
 
Progressive Parts, performance parts and tuning specialists