LCR .. twin fans
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dav138
Guest
Well i've changed both fans , fan control module & Radiator thermo switch and still nothing!! Fans now work both speeds if i wire across the switch, but are not kicking in on temp had it up to 100C nothing! even put old rad switch back in same 
Hi all,
Dav138, just curious, how did you manage to solve the radiator-fan puzzle?
My fans are sometimes(!) NOT kicking in, either.
Otherwise, working fine (constantly on slow speed) with the aircon switched on. Also, replaced the termoswitch on the radiator trying to fix the issue.
(Sorry to revive, did a lot of reading and still didn't hit the bottom).
Dav138, just curious, how did you manage to solve the radiator-fan puzzle?
My fans are sometimes(!) NOT kicking in, either.
Otherwise, working fine (constantly on slow speed) with the aircon switched on. Also, replaced the termoswitch on the radiator trying to fix the issue.
(Sorry to revive, did a lot of reading and still didn't hit the bottom).
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dav138
Guest
Had to change both fans in the end, you can check them by pulling the plug off the fan control module and run a wire straight to the battery, both should spin at 2 speeds else there dead. Fans cost £250 ish for both, managed to get cowling and fans off without taking out the rad just took some pipes off, bit of a job tho!
dav138, it sounds like you changed everything, and still, the fans wouldn't work automatically, but would when you switched the air con on? (yet, you then say, you fixed it by replacing the fans????)
I've got a similar sounding problem to you and Crize where the fans work at both speeds when doing the test by wiring the fan thermo switch connector, they come on at low speed when you switch the air-con on, but refuse to come on up to 99 DegC, (according to the CTS temp (a brand new sensor) via Vagcom). I replaced the fan thermostatic switch as everything pointed to that, but it's doing it also, still, with a brand new Topran thermostatic fan switch.
It doesn't make any sense, hence why mine (and presumably, Crize's interest) in your post.
Looking at the wiring diagram, I can't see how it can be anything other than the fan switch, if the fan spins when you wire it up directly (as per the usual test). The only other thing I can think of is that the quoted temps for the fan switch, are too low (does anybody know where they came from or can confirm they are correct?).
I'm going to wire my old fan switch up and dangle it in some boiling water, to see if I can make it "close".
Thoughts?
Cheers,
Matt.
I've got a similar sounding problem to you and Crize where the fans work at both speeds when doing the test by wiring the fan thermo switch connector, they come on at low speed when you switch the air-con on, but refuse to come on up to 99 DegC, (according to the CTS temp (a brand new sensor) via Vagcom). I replaced the fan thermostatic switch as everything pointed to that, but it's doing it also, still, with a brand new Topran thermostatic fan switch.
It doesn't make any sense, hence why mine (and presumably, Crize's interest) in your post.
Looking at the wiring diagram, I can't see how it can be anything other than the fan switch, if the fan spins when you wire it up directly (as per the usual test). The only other thing I can think of is that the quoted temps for the fan switch, are too low (does anybody know where they came from or can confirm they are correct?).
I'm going to wire my old fan switch up and dangle it in some boiling water, to see if I can make it "close".
Thoughts?
Cheers,
Matt.
dav138
Guest
It turned out to be, what I think in the end was an air lock in the rad, the switch wasn't getting hot enough to set the fans off. Filled rad from top hose and took for blast then the fans started working correctly!?
Interesting, thanks.
As I first spotted the problem only after changing the stat, and re-filling (all the coolant that came out, was filtered and went back in, and the level ended up being about the same). I drained the system this weekend again, and changed the CTS and fan switch, and again, put the coolant that came out, back in (it was very clean so I didn't bother filtering this time). Both times, it seemed to self-bleed fine, but both times, the fans still won't get auto-switched on, so I was wondering if there might be some inexplicable air bubble in that part of the rad (sounds pretty far fetched, but if it sounds like that's what happened to you, then perhaps not as far fetched as you (I ) might think! ).
That or the connector isn't quite mating with the prongs on the switch, but that sounds pretty far fetched also...
Did you disconnect the top hose from the CTS end to use to fill the rad? I wonder if you could prove/dis-prove this by loosening the fan switch and see if you get any leakage? You might even be able to bleed it this way to some degree, perhaps?
Cheers,
Matt.
As I first spotted the problem only after changing the stat, and re-filling (all the coolant that came out, was filtered and went back in, and the level ended up being about the same). I drained the system this weekend again, and changed the CTS and fan switch, and again, put the coolant that came out, back in (it was very clean so I didn't bother filtering this time). Both times, it seemed to self-bleed fine, but both times, the fans still won't get auto-switched on, so I was wondering if there might be some inexplicable air bubble in that part of the rad (sounds pretty far fetched, but if it sounds like that's what happened to you, then perhaps not as far fetched as you (I
) might think! ).That or the connector isn't quite mating with the prongs on the switch, but that sounds pretty far fetched also...
Did you disconnect the top hose from the CTS end to use to fill the rad? I wonder if you could prove/dis-prove this by loosening the fan switch and see if you get any leakage? You might even be able to bleed it this way to some degree, perhaps?
Cheers,
Matt.
Success
Looks like I fixed it (that, or I just didn't wait long enough for the fans to kick in when testing post re-fill/bleed (car got to 99 and I gave up waiting for the fans to kick in)).
This time I put the car up on a slope so the front right (rght hand drive offside) was definately the highest point (and at a nice slopey angle, to encourage any bubbles in the rad to move), and bled the system including squeezing the pipes, and revving the car to 3000rpm, until the CTS on VAGCOM reported about 93 DegC (and the coolant was starting to steam). I then put the cap back on and went for a high rpm thrash, including putting the heater on max temp and fan. I then let it sit and idle and the low speed fan now kicks in at a reported 99, the fan runs for about 10 seconds, by which time the temp has dropped to 96 and the fans shut off again.
In case it's of any use to anyone.
Cheers,
Matt.
Looks like I fixed it (that, or I just didn't wait long enough for the fans to kick in when testing post re-fill/bleed (car got to 99 and I gave up waiting for the fans to kick in)).
This time I put the car up on a slope so the front right (rght hand drive offside) was definately the highest point (and at a nice slopey angle, to encourage any bubbles in the rad to move), and bled the system including squeezing the pipes, and revving the car to 3000rpm, until the CTS on VAGCOM reported about 93 DegC (and the coolant was starting to steam). I then put the cap back on and went for a high rpm thrash, including putting the heater on max temp and fan. I then let it sit and idle and the low speed fan now kicks in at a reported 99, the fan runs for about 10 seconds, by which time the temp has dropped to 96 and the fans shut off again.
In case it's of any use to anyone.
Cheers,
Matt.
I bought my TT as non runner so not sure if fans ever worked, now rebuilt the engine with new clutch etc but the fans dont cut in at all - All fuses are ok, replaced fan switch with non genuine item ran car upto 100oC but fans dont kick in, if i disconnect plug from fan switch and put a tester across then the tester glows up faintly and the fans cut in and out while the ignition is on. I have also replaced fan control module but still same issue. Now fed up and wondering what it could be.
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yeah, I have same problem, so does lmiller at the moment - he recently did a slow speed fan fix and his don't come on till the temp hits 102oC. I'm hoping it's an air lock, like mutant_matt and dav138 had. Sounds like a pretty common problem if so. My car has a relatively new water pump and thermostat, new fans, and a new thermoswitch, and I have this problem. Only thing I haven't changed is the fan control module, but like you, my fans come on when the pins are bridged on the thermoswitch. it MUST be that the thermoswitch is not getting up to temp.
dav138
Guest
Switch your air con on fans should spin at low speed else new fans prob needed, I took fans off wired them straight to battery and didn't spin at all. Got 2 new fans, wired to battery span both speeds, fitted to car left to run up hot enough to set off fans nothing, changed fan switch module nothing, changed thermo switch nothing, took out for blast!! suddenly fans started working and have been fine ever since.For me fans were done defo done and can only be a coolant air lock causing thermo switch not getting hot enough!
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