Air Con Troubles

[Dazza95]

Nice work guys

Just to close this one out for anyone experiencing problems as per my initial post; the first thing to do is to scan for fault codes. The fault codes and advice on here led me to check the wiring to the compressor (more specifically, the N280 control valve), this wiring was damaged and repairing it got the compressor running.

The second issue was the cooling fan only operating on high speed, for proper and correct operation, it should work at low speed when the AC is running - it shouldn't pulse at high speed. I suspect the issue with mine was the resistor for low speed within the fan as described above. A new fan solved the problem, however if your low speed doesn't work it could be other things such as the fan controller, wiring etc. To check the fan(s), with the engine running, put the AC on and turn the temperature knob all the way to the left, the cooling fans at the front of the engine bay should run at low speed (it may take a minute or so to come on). Low speed operation is pretty much silent, high speed you can hear from the car. If using VCDS, check meas block 01 and 02 - 'cooling fan stage 1' should be on. You shouldn't have any compressor shut off codes in meas block 02 for the test to be accurate.

I monitored the system today using Meas Block 01-04 and with the system set to full cooling, the temperature at the centre vents went as low as 2c after around 20 minutes. The cooling fan stayed at low speed thoughout (stage 1).

Hope this helps, I've learnt quite a bit about the system in trying to get it all working correctly.

Edited 28 May, 2016 by Dazza95

[Breezy_Pete]

Nice summary fella.

Only thing I would say is that VCDS doesn't actually tell you if only one (if you have two) fan is running, in fact I'm not sure it actually tells you that any are; just that the relevant relay is energised. Best to eyeball them as well.

Soldering my resistors in after tea.

[Breezy_Pete]

Haaaaaaaaaaarsh!

All wired in and now the main fan starts up at low speed correctly but the little one doesn't (unless you give it helping poke with a finger)

 

       

 

Noticed when comparing things with the missus's car last week that her second/smaller fan spun much faster and more smoothly than mine, I guess the power the main one's now using is dropping the voltage enough at the relay output that the other one won't start without help...  Small fan has maybe worn itself out trying to do its job and that of the other one for however long? 

 

Now I've got to extract the small fan and see about mending that or replacing it.

 

I was so looking forward to both fans starting up happily...

[VWD]

Someone mentioned resistor ends heating up. In high power radio transmitters in the 70's, we used to solder the tuning coils with resin cored plumbing solder, as the heat changes could crack normal solder. Nice idea using a heat shield, but if the design had been thought thought through at design stage, the resistors it might have been better to put the control in the negative lead to the fan ,and use the chassis to aid heat sink. On a similar vein ,it would be easily possibly to design a PWM control unit for the fans ( I'd suggest that it would only add  an extra bit of circuitry to the CPU), but again the problem of heat sinking the control electronics.

[Dazza95]

Nice summary fella.

Only thing I would say is that VCDS doesn't actually tell you if only one (if you have two) fan is running, in fact I'm not sure it actually tells you that any are; just that the relevant relay is energised. Best to eyeball them as well.

Soldering my resistors in after tea.

That does make sense. Forgot to add that I allso cleaned the condenser, it's easily accessed with the bonnet open - used a degreaser, let it sit for a while and then hosed off. I did get quite a few bugs and general grime out.

[Dazza95]

Haaaaaaaaaaarsh!

All wired in and now the main fan starts up at low speed correctly but the little one doesn't (unless you give it helping poke with a finger)

Noticed when comparing things with the missus's car last week that her second/smaller fan spun much faster and more smoothly than mine, I guess the power the main one's now using is dropping the voltage enough at the relay output that the other one won't start without help... Small fan has maybe worn itself out trying to do its job and that of the other one for however long?

Now I've got to extract the small fan and see about mending that or replacing it.

I was so looking forward to both fans starting up happily...

What a shame! I guess you're not exactly sure about just how long the small fan has been 'overworked' as it were. Keep us posted on how you get on

[Breezy_Pete]

What a shame! I guess you're not exactly sure about just how long the small fan has been 'overworked' as it were. Keep us posted on how you get on

Found a replacement Meyle fan on ebay for £33odd so hopefully that'll go on next weekend.

[Breezy_Pete]

Finally some good news. Took the old small fan out yesterday, just to see how to do it. Unlike the main fan, the fixings aren't visible, being on the outside/front of the fan cowling moulding, rather than the engine side.

So the whole cowling has to come out, which isn't super-easy if you've never done it before. I'll do a little how-to on this soon, after checking that the Fabia is identical enough for it to be worthwhile. I took a bunch of photos as I put it back in today.

 

The good news is that the small fan I took out was fixable without too much effort . Once I'd prised off the steel lid, I could see that there are four carbon brushes, two of which were stuck in their holders, no longer reaching the commutator. The whole wiring and brush arrangement sits on a removable plastic housing which just prises out. A bit of a free-up and clean-up and I was fairly sure things would be much better. Gave the commutator a quick whizz-over with some 800-grade wet-n-dry while I was at it. (Sorry no pics of that, phone was on charge indoors).

 

Reassembled everything and fired up the engine, switched on the AC, had the phone on video pointing at the fans as I waited for them to cut in together on demand from the AC, and nothing happened for twenty or thirty seconds. Wandered back to check I'd switched on the AC, and just as I was getting back round with the phone, they ​both started up good as gold. The small fan was understandably giving it much more beans than I've ever seen it do before, almost seeming like it was on high speed (but it's only single speed). :sun:

 

Never really thought about it before but presumably that small fan, 'cos of where it is, not only helps by pulling air through the condenser, but also shoving that air past the compressor (and alternator) giving both of them some active cooling. It certainly shifts some air!

 

Will try to cancel my order for the new fan (not yet dispatched). Fingers crossed that'll be OK. 

 

Happy screenshot of AC-related measuring blocks, cabin fan on 2, engine idling, super-cooool (and pressure well down on what it was last time I looked, with only the small fan running sloooowly):

 

 

  :cocktail: :wine:

Edited 30 May, 2016 by Wino

[del-gti]

Excellent. Well done getting it sorted. I love it when a plan comes together.

I really should do some vcds work to see if the figures are as they should be.

[Dazza95]

Will try to cancel my order for the new fan (not yet dispatched). Fingers crossed that'll be OK. 

 

Happy screenshot of AC-related measuring blocks, cabin fan on 2, engine idling, super-cooool (and pressure well down on what it was last time I looked, with only the small fan running sloooowly):

 

 

  :cocktail: :wine:

 

Excellent, it must have been chilly with the interior as cold as 16ºc! When I tested mine it was around 21ºc outside but the car was sitting in the sun, the temperature at the AC panel was reading 38ºc but I sweated/suffocated for a while to test it  properly   I've seen a few posts on here saying the AC isn't very good in the Fabia but I think it works rather well at regulating the temperature, I rarely have mine set anything below 18ºc.

[Breezy_Pete]

 Now that you mention it, I guess the AC had a headstart with ambient air at that sort of temperature! Didn't think of that  .​ ​

Still reckon things are going to be much better next time it is warm.

[del-gti]

Was 24 degrees here today and the car was ice cold inside! Normally I'd be dreading a drive home from work in this weather.

Such a good little fix to get the a/c working again.

Thanks to all who had some input in this thread, I probably wouldn't have had a go at fixing mine otherwise.

[Alexandru]

Anybody here had a problem with the ac compressor whining when running ? 

[Dazza95]

Anybody here had a problem with the ac compressor whining when running ?

I haven't, have you got a recording of how it sounds?

[Alexandru]

I will upload a clip later.

Sent from my iPhone using Tapatalk

[Alexandru]

I couldn't make it whine today ... there were about 19-20 Celsius degrees outside and all I managed to achieve was condensation on the outside of the windshield.

[Alexandru]

 

Initially, AC is switch on and the whining is pretty much there. At 0:16 I'm turning off the AC, idling settles at 800rpm and the whining gets away. It doesn't do this every time AC is switched on, but in the past 3 years it got worse. Is it a failing bearing ?

Edited 13 June, 2016 by Alexandru

[Tech1e]

Possibly. Needs diagnosis with a stethoscope to see if that's where it's originating from.

[Alexandru]

Oh .. ok .. that's good to know ! It shows no errors in a standard ECU scan with VCDS.

[Alexandru]

Update: could it be a faulty alternator bearing causing this noise, due to the belt being stressed when ac compressor being under load?

Sent from my iPhone using Tapatalk

[del-gti]

Bit of a thread resurrection here, but it's a good thread with lots of useful info and we are getting to that time of the year when the a/c takes a hammering... 

 

...just a bit of an update. My a/c is still working! Woohoo! Did have to get it regassed at the weekend as it wasn't quite as cold as it had been and I was starting to get a faint hissing sound from behind the dash again. This, to me is the tell-tale sound that it's low on refrigerant, so a slight leak is likely. 

 

Still I'm happy to pay for a regas once a year if it means a nice cold interior. 

[Pashley2496]

Hi all, some interesting information on this thread. Recently bought this car and trying to get the A/C working, got told by previous owner A/C didn't work as it needed re-gassing.  Managed to pull out nearly all the refrigerant and no leaks when vacuum tested. It wouldn't take the full 525g, only about 465g and still wasn't cold. So I plugged into VCDS and got these codes. Any pointers where to start as it seems a lot of codes. Thanks all

VCDS HVAC.txt

1 minute ago, Pashley2496 said:

Hi all, some interesting information on this thread. Recently bought this car and trying to get the A/C working, got told by previous owner A/C didn't work as it needed re-gassing.  Managed to pull out nearly all the refrigerant and no leaks when vacuum tested. It wouldn't take the full 525g, only about 465g and still wasn't cold. So I plugged into VCDS and got these codes. Any pointers where to start as it seems a lot of codes. Thanks all

VCDS HVAC.txt 1.31 kB · 0 downloads

                Address 08: Auto HVAC       Labels: 6Q0-820-045.lbl
Control Module Part Number: 6Y0 820 045 
  Component and/or Version: Klimaanlage        X0830
           Software Coding: 
            Work Shop Code:   
                      VCID: 72EA51C03EC9901404-5140
7 Faults Found:

01271 - Positioning Motor for Temperature Flap (V68) 
            41-00 - Blocked or No Voltage
01596 - Motor for Outside/Recirculated Air Flap (V154) 
            41-00 - Blocked or No Voltage
01596 - Motor for Outside/Recirculated Air Flap (V154) 
            55-00 - Adaptation Not Successful
00819 - High Pressure Sensor (G65) 
            28-00 - Short to Plus
00898 - Control Circuit A/C compressor 
            30-00 - Open or Short to Plus
00706 - Relay for Coolant Fan; Stage 2 (J513) 
            31-00 - Open or Short to Ground
01317 - Control Module in Instrument Cluster (J285) 
            79-00 - Please Check Fault Codes

[sepulchrave]

Start by clearing the lot and trying again, moving the knob back and forth between hot and cold should unstick the temperature flap. Fan relay is a simple swap but you should test the fan first to ensure it's not burnt out.

[Breezy_Pete]

Strip fuse no. 5 in the battery fuse compartment also worth checking with regard to 00706.  Blade fuses no. 8 and 11 are also worth checking while you are there, under the plastic cover beyond strip fuse no. 6. Both fan-related.

Recirculation faults will be irrelevant and not worth fixing.

00819 and 00898 may be broken wires, look at the two-way brown connector pair on the bracket in front of the gearbox for the 00898 fault, and the high pressure sensor just in front of the coolant expansion tank for the other.  

The G65 high pressure sensor sometimes has corrosion damage to its connection pins, and the mating sockets of the loom connector, so carefully disconnect and examine that connector for a look.  Check youtube for tips on disconnecting VW-type connectors if you aren't familiar with the technique.

Edited 20 June, 2021 by Wino