Neither of my radiator fans seem to be working at all. Air con has been blowing out ice cold air all summer.

It was pointed out to me that Fuse No5 (strip fuse on top of battery) had blown along with Fuse No 8 (again on battery).

 

Thermostat was replaced yesterday along with coolant. (Just mentioning as it may or may not be part of the issue)

 

Fuse 8 replaced and thusfar not blown. Same with Fuse 5 but still the rad fans won't kick in??

 

Some logs;

 

VCDS-Lite Version: Release 1.2
Sunday, 04 December 2016, 11:59:42:25095
Control Module Part Number: 6Y0 820 045
  Component and/or Version: Klimaanlage        X0830
           Software Coding:
            Work Shop Code:
                      VCID: F297BBCCADB7
3 Faults Found:
01271 -  Positioning Motor for Temperature Flap (V68)
        30-10 -  Open or Short to Plus - Intermittent
01596 -  Motor for Outside/Recirculated Air Flap (V154)
        30-00 -  Open or Short to Plus
01596 -  Motor for Outside/Recirculated Air Flap (V154)
        29-00 -  Short to Ground

Live Data logs

Fan Pos 1 Fan Pos 2 Fan Pos 3 Fan Pos 4 Temps

 

Taken the car for a good blast up and down the motorway and the temp gauge sits bang in the middle, no temp warning light coming on. Heater blowing hot air when it should and ice cold air when set to A/C.

 

Any thoughts people?

 

TIA

So we know what we're dealing with have a look at the smaller fan and see if it has the same mounting as the main fan (three-legged bracket accessible from engine side), and how many wires are visible going into its motor.  The picture here is of the main fan on my Polo, not the small/AC one, because mine is different in respect of mounting arrangement and where the wires emerge, but I think yours may be the same for both. 

 

Are there two or three wires going to the smaller fan?

 

 

Since VCDS thinks it's turning the fans on, it could be a faulty fan control module, but I think much more likely both fans have broken internal low-speed resistors.  Normally high speed operation would start when the fans are already spinning at low speed, so less 'stressful' electrically.  I think because your low speed isn't working on either fan, the current surge of trying to start up both on full speed from a standstill is enough to bust the 40A stripfuse.  This would be a more likely explanation if both fans are indeed twin-speed/three-wired.

There's definitely three wires going to the smaller fan (on the drivers side). I can't quite see how many are going to the larger fan on the N/S.

There will definitely be three wires going to the main rad fan, they're all two-speed.

 

First thing to try is to bypass the fan control module, to prove that both fans have lost their low speed due to the internal resistor failing (rather than anything to do with the fan control module). 

If you unplug the large four-way connector from the fan control module and use a thickish bit of copper wire to bridge the two smaller pins of the loom connector, both fans should come on at low speed (as long as fuse 8 in the batt box fuseholder is still OK).  If they don't, stick a multimeter on the pin that goes to the fans (the arrowed one in this pic) and measure resistance from there to chassis/batt neg.  Expect a high resistance if the fans have failed low speed resistors.

 

 

Once you've confirmed this, you have some choices.

 

Short-term, easiest 'fix' is to buy and fit a new 40A strip fuse, but then disconnect  (just) the main rad fan at its (3-way, rectangular) connector near the bottom corner of the rad.  This will mean that your AC fan should now come on, when G65 pressure demands, at full speed without unduly stressing the fuse or the relay inside the fan control module. That'll get you through to springtime with reduced risk to the AC system. The small/AC fan will now keep the refrigerant pressure under some control, reducing the risk of leakage at O-rings, and reducing the back-pressure on the compressor.   Somewhere in one of the posts I've written on this subject, there are some plots of refrigerant pressure and how the fans keep it within some limits, if the fans are working right/at all.  In a nutshell, the low speed fan action happens once 9 bar pressure is registered at G65, the full speed operation at 16 bar. 30+ bar, as you're seeing, shouldn't be happening, I think.  Surprised that doesn't cause the system to shut down.

 

A better fix would be to repair or replace at least one, if not both fans.  Repair can be done cheaply, but it's not really a mid-winter outdoorsy sort of job.

 

See here for discussions of, and links to the 'external low-speed resistor' fix.

Edited 4 December, 20169 yr by Wino

I ran out of time to investigate any further today, Wino but I do appreciate the effort you've put into your post :thumbup:

 

Whilst at the scrapyard today looking for a half decent boot trim I decided to get as many strip fuses as I could from various VAG cars. It seems you can only remove them from Fabias and Polos with a standard 3/8 drive socket. For others you'll need a slim socket but they all appear to be retained with a 10mm nut.

It's worth doing as TPS charge ~ £4.50 for one of these fuses. Mine were, er, liberated

 

Pop them in some Viakal for a while to clean them up and help you to see the Amperage stamped on them for future reference.

Nice bit of resources-saving there, natural & manufacturing resources and financial.  I'm sure once upon a time I saw a suggestion that these fuses are made of aluminium, so be careful what you use to clean them up, try one or two rather than risk dissolving them all.  They don't seem very aluminiumish to me so that may be false info.

 

Couple of things I forgot to mention before. 

Firstly, if you do try shorting out the smaller pins of that 4-way of the fan control module to power the fans directly at low speed, don't be alarmed if you get a reasonable spark when you short them, the surge current will be significant if they do actually work.  There's no danger, it just might surprise you if you weren't expecting it.  I suspect you won't get any such spark, and the fans will do nothing, but worth the heads-up I think.  If you were to do the same with the big terminals, for full speed fan function, the spark will be bigger still.

 

Secondly; there's another fuse that's worth checking, which I only really became aware of yesterday thanks to something Clunkclick said in his battery drain thread. Fuse no.11 in the battery box fuse tray is a 5A fuse that powers the coil of the low-speed fans relay in the fan control module (except for late, 05/2006> cars where it's fuse 9) .  If that's blown you won't get any low speed function.  Unlikely to happen, but easy to check, so worth a look.   

Edited 4 December, 20169 yr by Wino

My magnet agrees with the suggestion that they are made of aluminium; if it sticks, it's steel, right?

 

I've just been out and pulled fuse 11 which is fine so we can eliminate that one from the investigation.

My magnet agrees with the suggestion that they are made of aluminium; if it sticks, it's steel, right?

 

 

 

Just tried a spare one I have lying around. Doesn't stick to my magnet either.

Well, yes a magnet will only stick to ferrous metals, but that just proves that the fuses aren't ferrous rather than that they are aluminium.

Just tried a spare one I have lying around. Doesn't stick to my magnet either.

Have you calibrated your magnet correctly?

Have you calibrated your magnet correctly?

 

Haha :p