Air Con Diagnosis help!

J

Jason_e

Member
Evening all,

I'm nearing the end of my Air Con Diagnostics and I'd thought I'd post my findings (so far) on here to see what you all think could be off.

So obviously, the AC does not run cold. I tend to leave it in ECO because of this, but even when I turn ECO "Off" I dont hear anything click in. Even so, I took it to get the AC regassed at a Halfords. Why? Well its £30ish and if they cant do it they dont charge. The guy said basically that according to their pressure gauge, my system was full. His best guess was that it wasnt opening fully or whatever.

I've sort've left it there but today I visited my friend and mechanic for a catch up, and while I was there I got him to add the locking blip on my car. Beforehand though he scanned my computer for a predictiably long list of faults. Baring in mind, ive never scanned this car since ive owned it!

The codes we got for the HVAC were numerous. But its worth mentioning again the car did sit for a period of time in my ownership with the battery disconnected. Furthermore, I have removed the HVAC control unit (For cosmetic fixes!) whilst the car had power so a lot of these couldve been that.

This is what we got with the first scan:

Code: 
Address 08: Auto HVAC        Labels: None
   Part No: 8Z0 820 043 D
   Component: A2-KLIMAVOLLAUTOMAT 0510 
   VCID: 3776FBD9153F87373E-258C

10 Faults Found:
00710 - Defroster Flap Positioning Motor (V107)
            41-10 - Blocked or No Voltage - Intermittent
01272 - Positioning Motor for Central Flap (V70)
            41-10 - Blocked or No Voltage - Intermittent
01271 - Positioning Motor for Temperature Flap (V68)
            41-10 - Blocked or No Voltage - Intermittent
00716 - Air recirculation Flap Positioning Motor (V113)
            41-10 - Blocked or No Voltage - Intermittent
00727 - Potentiometer in Positioning Motor for Defrost Flap (G135)
            30-10 - Open or Short to Plus - Intermittent
00601 - Potentiometer On Positioning Motor for Central Flap (G112)
            30-10 - Open or Short to Plus - Intermittent
00600 - Potentiometer On Positioning Motor for Temperature Flap (G92)
            30-10 - Open or Short to Plus - Intermittent
00735 - Potentiometer in Positioning Motor for Air recirculation Flap (G143)
            30-00 - Open or Short to Plus
00818 - Sensor for Evaporator Outlet Temperature (G263)
            30-00 - Open or Short to Plus
01273 - Fresh Air Blower (V2)
            17-10 - Control Difference - Intermittent

Then, we cleared them and ran the car, before running a second scan. These re appeared:

Code: 
Address 08: Auto HVAC        Labels: None
   Part No: 8Z0 820 043 D
   Component: A2-KLIMAVOLLAUTOMAT 0510 
   VCID: 3776FBD9153F87373E-2586

6 Faults Found:
00710 - Defroster Flap Positioning Motor (V107)
            41-10 - Blocked or No Voltage - Intermittent
01272 - Positioning Motor for Central Flap (V70)
            41-10 - Blocked or No Voltage - Intermittent
01271 - Positioning Motor for Temperature Flap (V68)
            41-10 - Blocked or No Voltage - Intermittent
00716 - Air recirculation Flap Positioning Motor (V113)
            41-10 - Blocked or No Voltage - Intermittent
00727 - Potentiometer in Positioning Motor for Defrost Flap (G135)
            30-10 - Open or Short to Plus - Intermittent
00735 - Potentiometer in Positioning Motor for Air recirculation Flap (G143)
            30-00 - Open or Short to Plus


Its worth saying (As it was the first thing my mechanic queried!) that I can control where the air flows without issue, ie to my feet or the screen etc. As well as the fan speed and whatever else. Its just the AC doesnt appear to be getting to the cabin...

A theory he had was that It may need to have a flap recalibration of sorts?

And as for the AC, is there any easy visual check on the A2 to see if the Condenser is kicking in?

Thanks in advanced for your help!
 
The VCDS scan tool can access additional data for the air conditioning and will be able to indicate the pressure in the system as well as the parameters for the compressor. This data will confirm if there is indeed pressure in the system and whether it's sufficient to operate correctly.

If the compressor is functioning, then you should be able to detect the difference in temperature of the pipes within the engine bay, the area above the gearbox is the most accessible, and you should be able to trace the pipes around the back of the engine to where they go through the bulkhead into the aircon system. If there is a difference in temperature then this confirms that the compressor if functioning, and perhaps it's simply the temperature control flap (V68) that is not working.

One way to restore the functionality of the control flaps is to try moving them through their full range by operating the selector buttons on the climate control, going from hot to cold, defrost to feet etc. Do this multiple times and you may have some success in getting the system to recognise their positions.
 
Mine was similar, I replaced the G263 sensor as it kept coming up as a fault, cleared the codes and it wouldn’t work, the next day it started working.
 
Seem the flap motors are notorious errors, most people ignore them. The compressor is not magnetic clutch, it's continously compressing. It varies the compression using a sliding internal adjustment. The eco button limits ac to something low like 5-10% ac 95-90 fresh air to save working the engine. So you won't hear a click. The pulley has a rubber clutch failsafe. If the flaps work that's great, but it's the temperature mixer flap that needs to work v68? And the compressor of course. If the system is pressurised correctly and pipes get cold it must be the temp flap.. not the easiest to diagnose but good luck! I use a mobile specialist in ac as there's more to it than you think, you need the right pressure on both sides of sytem and also right pressure at given ambient temps to prove its working.
 
The scan seems to indicate that all of the moving flaps are faulty. This is unlikely, one or two possibly, but not all.
I'd have a look at the connections to the HVAC module.
Mac.
 
I think the flaps errors come up a lot even if they work, mine did and they work fine now, tempermental, funny that in an A2 !! :cool:
 
Thanks for the advice all!

My guy did remark how he thought it was odd all the flap errors were listed as "Intermittent" given we cleared them and scanned right after, hence the reasoning that perhaps its a calibration issue of some sorts. But if its just a common error code to get on these that also makes sense.

I'm actually off work with bloody Covid! So I cant take it back for more scannage. However, I may do some more practical fault-finding as listed above to see if I can at least rule out the compressor and the connections on the HVAC panel itself.
 
If the face plate of the compressor spins while the engine is off then the rubber clutch failsafe is broke and you wont have drive for the compressor. As its constantly on if something goes wrong the rubber join is designed to shear to let the belt keep spinning, i.e if the compressor siezes. Then the belt stay on. Youll need a new compressor really, you can find a polo one but it obviously has to be the non electro clutch one, very similar codes so be careful, come back if you need one, I have a polo one ready to fit so can get code of it. I paid £30 for mine. You really dont want issues within the HVAC unit itself as its entire dash out and the plastic in the dash areas is brittle as you like. Having recently disseccted the HVAC unit completely I found the evaporator very well sealed and in good condition so I think your problem lies with either compressor or a blockage somewhere. Let us know! Im still trying to find time to fit new belt, accumaltor compressor/dryer, condensor and turbo intercooler. I need it to coincide with someone regassing and oiling the AC before i then start engine though!
 
I think you'll find somewhere in Ross Tech that all intermittent fault codes associated with A/C should be ignored!

RAB
 
CrispyEdd said:
If the face plate of the compressor spins while the engine is off then the rubber clutch failsafe is broke and you wont have drive for the compressor. As its constantly on if something goes wrong the rubber join is designed to shear to let the belt keep spinning, i.e if the compressor siezes. Then the belt stay on. Youll need a new compressor really, you can find a polo one but it obviously has to be the non electro clutch one, very similar codes so be careful, come back if you need one, I have a polo one ready to fit so can get code of it. I paid £30 for mine. You really dont want issues within the HVAC unit itself as its entire dash out and the plastic in the dash areas is brittle as you like. Having recently disseccted the HVAC unit completely I found the evaporator very well sealed and in good condition so I think your problem lies with either compressor or a blockage somewhere. Let us know! Im still trying to find time to fit new belt, accumaltor compressor/dryer, condensor and turbo intercooler. I need it to coincide with someone regassing and oiling the AC before i then start engine though!
Click to expand...

Had a look under the bonnet with and without the engine on, my findings:

  • Face plate of the compressor does not spin freely with the engine off - that would suggest the rubber failsafe is okay.
  • When the engine is on, everything spins as expected (With ECON on or not)
  • The pipes appear to be getting cold to the touch, all the way round to the bulkhead
  • Blowers in the cabin, no matter where they're pointing, do not get colder. Even in full LO setting
 
As above - looks like you have a prime suspect Jason. This is a recognised common fault that should hopefully be a free (or at least cheap) fix
 
Take your time reading up on the refit of the v68 it's tricky . Yes an a2 job that's tricky! There are two designs of v68 I think it's number of teeth so you really need to take it off to get a look at teeth count and shape but it has to go back on in same place. I may have the spare you need.
 
Catnip64 said:
If you are sure that the pipes are getting cold as they go into the bulkhead then it suggests that the temperature flap, V68 is stuck in the 'hot' position. If exercising the temperature buttons up/down doesn't help, then have a look at this thread to see where it's located so that you can take a look to see if it's actually moving.
https://www.a2oc.net/community/index.php?threads/temp-flap-positoning-motor-v68.15946/
Click to expand...
Hi - piggybacking off this thread as I know own Jason's old car.

The links in the thread you recommended are dead and when I search the forum for V68 it says something went wrong!

I would quite like my AC working in this weather, is it a DIY job or am I better off just biting bullet and going to a VAG Garage?
 
A2FJT said:
Hi - piggybacking off this thread as I know own Jason's old car.

The links in the thread you recommended are dead and when I search the forum for V68 it says something went wrong!

I would quite like my AC working in this weather, is it a DIY job or am I better off just biting bullet and going to a VAG Garage?
Click to expand...

Quote 'when I search the forum for V68 it says something went wrong!'

Unfortunately the Forum search engine needs at least 4 digits to work.

Cheers Spike
 
A2FJT said:
Hi - piggybacking off this thread as I know own Jason's old car.

The links in the thread you recommended are dead and when I search the forum for V68 it says something went wrong!

I would quite like my AC working in this weather, is it a DIY job or am I better off just biting bullet and going to a VAG Garage?
Click to expand...
Yes, it was a while ago but the link to the German forum with pictures of the climate control system still works. Note however that LHD/RHD systems are not the same!
 
A2FJT said:
I would quite like my AC working in this weather, is it a DIY job or am I better off just biting bullet and going to a VAG Garage?
Click to expand...

What happens when you lower the temperature setting right down to 'Lo'?
 
steve_c said:
What happens when you lower the temperature setting right down to 'Lo'?
Click to expand...
It feels like blows ambient air whenever you set it below outdoor temperature. Jason did some diagnosis above but I haven't checked since I bought it
 
You must log in or register to reply here.
Back
Top