A/C fans not working

Chat about your MKV (6N2) Polo GTi
M7R
New
Posts: 41
Joined: Sat Jul 14, 2012 1:55 pm

Re: A/C fans not working

Post by M7R »

Yeah I had seen the bolts on the u it was working out where they are on the actual car that was the pain, when I had the battery tray off it’s was obvious where they were. Will be a week or so until I can have another look at the car. This is a personal challenge now I won’t be beaten by the bloody thing!
User avatar
937carrera
Silver Member
Posts: 427
Joined: Sat May 17, 2014 8:19 am
Drives: 2000 Polo GTi
Location: North Yorkshire

Re: A/C fans not working

Post by 937carrera »

Good !....... because I struggled to get them out on mine :wink:

Give 'em plenty of time to soak with penetrating oil
M7R
New
Posts: 41
Joined: Sat Jul 14, 2012 1:55 pm

Re: A/C fans not working

Post by M7R »

Ahhh sorry no what I meant was I have seen that the bolts are on top of the unit, but I’m not sure where they actually are from above. Any clues as to where I need to aim the WD40?
User avatar
937carrera
Silver Member
Posts: 427
Joined: Sat May 17, 2014 8:19 am
Drives: 2000 Polo GTi
Location: North Yorkshire

Re: A/C fans not working

Post by 937carrera »

Ah, my memory is a bit rusty as it's a few years ago, maybe this will help = there's a sub plate involved
Attachments
fan_control.jpg
M7R
New
Posts: 41
Joined: Sat Jul 14, 2012 1:55 pm

Re: A/C fans not working

Post by M7R »

Ahhh okay I’ll have a poke around, hopefully I can do it I’m my lunch hour.

Cheers
M7R
New
Posts: 41
Joined: Sat Jul 14, 2012 1:55 pm

Re: A/C fans not working

Post by M7R »

New control box plugged in, and it’s still the same. When shorting 2 and 3 on the rad temp nothing happens.

I will get the AC regassed anyway just to rule that out. The compressor kicks in though as you can clearly hear it click in when you turn off econ.
User avatar
937carrera
Silver Member
Posts: 427
Joined: Sat May 17, 2014 8:19 am
Drives: 2000 Polo GTi
Location: North Yorkshire

Re: A/C fans not working

Post by 937carrera »

So, if you effectively close the "high speed" switch on the thermoswitch, what you are effectively doing is providing current to terminal 3 of T10h - but only switching current, look at the size of the wire.

Through the control unit, terminal 1 of T4h should then provide the motor with power at full current to run the fan on high speed.

As the fan is not running on high speed then the following are possibilities - check the wiring diagrams I uploaded

1. There is a break in the wire to the control unit
2. The control unit is defective (two bad ones)
3. The control unit is not receiving current to power the fan (check fuses 4 and 8 )
4. There is a break in the power cable from the control unit to the fan.

All the above is irrelevant as to what the ACC system status is.

Simple things first, recheck the fuses, then run a test cable direct from the battery to terminal 1 on the motor.

Assuming the fuses are fine, and the motor runs on high speed with a battery feed (and why not, it runs at low speed with a resistor in series), then you need to be running continuity / voltage checks around the rest of the circuit.
M7R
New
Posts: 41
Joined: Sat Jul 14, 2012 1:55 pm

Re: A/C fans not working

Post by M7R »

I get what our saying, I have high speed but not low speed though.

I had started to try and follow the wiring diagrams, not my favourite thing to do if I’m honest I prefer mechanical things rather than black magic from little boxes.. but needs must as this is annoying me loads now.
User avatar
937carrera
Silver Member
Posts: 427
Joined: Sat May 17, 2014 8:19 am
Drives: 2000 Polo GTi
Location: North Yorkshire

Re: A/C fans not working

Post by 937carrera »

M7R wrote: Wed Jun 05, 2019 12:47 pm When shorting 2 and 3 on the rad temp nothing happens.
That's what you said.... and if you look at the wiring diagram on F18, 2 & 3 are the contacts for speed II while 2 & 1 are for speed I

Easiest test to do for now is the provide battery live to terminal 1 (high) and terminal 2 (low).

If it doesn't work on low speed then it'll be the internal resistor that has failed (the rectangular box in the motor icon)
M7R
New
Posts: 41
Joined: Sat Jul 14, 2012 1:55 pm

Re: A/C fans not working

Post by M7R »

Hmmm I’ll have another look on Friday as when I shorted the one set of pins that do run the fan it’s going flat out! If it can o any faster I will be surprised!

Will try power straight to the fan and see how fast it goes then.
M7R
New
Posts: 41
Joined: Sat Jul 14, 2012 1:55 pm

Re: A/C fans not working

Post by M7R »

https://www.clubpolo.co.uk/uploads/mont ... 336381.jpg

Looking at this I have high speed. Shorting 2 and 3 the fan runs full chat. Shorting 1 to either 2 or 3 does nothing.

Checking with a volt meter there is nothing between 1 and 2, and 12v between 2 and 3.

I have also checked the fuses on top of the battery and they seem fine,
User avatar
937carrera
Silver Member
Posts: 427
Joined: Sat May 17, 2014 8:19 am
Drives: 2000 Polo GTi
Location: North Yorkshire

Re: A/C fans not working

Post by 937carrera »

Go back to the wiring diagrams I posted earlier

On F18 terminal 2 is 12V feed to the thermoswitch

1 and 3 are the connections for the switched voltage to ECU

3 is the high speed connection to the ECU, which then provides the high current voltage direct to the motor on current track 20 to 26 (terminal 1 on the motor)

2. is the low speed connection to the ECU ...... AND ........ the motor on low speed in current track 27 terminal 2
937carrera wrote: Wed Jun 05, 2019 4:54 pm If it doesn't work on low speed then it'll be the internal resistor that has failed (the rectangular box in the motor icon)
Final check, just put battery 12v onto terminal 2 of the motor and provide an earth on terminal 3. If it doesn't spin it's the resistor
M7R
New
Posts: 41
Joined: Sat Jul 14, 2012 1:55 pm

Re: A/C fans not working

Post by M7R »

Sorry I had 15 mins at lunch in the car park to have a play, so did the quick and easy bits.

So as another quick check, if I give 12v to terminal 2 of the motor and an earth to terminal 3, and nothing happens then a new fan motor is needed?

By 12v to the fan I assume you mean to the connector that is near the battery, the 3 wires of which go straight off into the fan. I can do this pretty quick before home time if so.
User avatar
937carrera
Silver Member
Posts: 427
Joined: Sat May 17, 2014 8:19 am
Drives: 2000 Polo GTi
Location: North Yorkshire

Re: A/C fans not working

Post by 937carrera »

I didn't talk about the fan, I talked about the motor, i.e the connections actually on the motor for the fan.

Any yes, the test in your second paragraph is what you need to do.

You're lucky, I am working on a 6N2 Polo GTi at the moment, so yes, it's the 3 pin connector fastened onto the battery plate.

1+3 earth = high speed

2+3 earth = low speed
M7R
New
Posts: 41
Joined: Sat Jul 14, 2012 1:55 pm

Re: A/C fans not working

Post by M7R »

Well had a look and a play, and the motors dead. High speed when direct to the battery it runs flat out, connect 2 and 3 to the battery and nothing at all!

So ordered a new fan and I will fit it next week one lunch as it doesn’t look too hard (famous last words!). Then regard the AC and hopefully that’s it sorted!
Post Reply