Climate control - electrical problem - help needed!

[JohnHighfield]

I post this update in the hope that there is someone out there in the forum that knows exactly what this problem is…..

Outline of problem.

This seemed to happen in a period of heavy rain – some 5 weeks ago - which I thought may have been connected..

The power supply to climate control seems intermittent as the unit switches on/off repeatedly (when on it seems to perform ok) but it only stays on for a few minutes.

Initially it stays on for longer periods but the 'on' time decreases over time & after about 20 mins tends to be 'off' most of the time with just the occasional on flick 'on'.

• These other problems may or may not be connected – but they seemed to have occurred at the same time & are all electrical…
• The external temp info on the driver’s info panel on the dash tends to go blank (after about 10 mins) and then throws up odd temps- ie -56F.
• The gear indicator – on the drivers info display - sometimes comes up showing all gears lit up – this does tend to re-set itself once underway.
• The engine temp gauge does not seem to be working now.

An Audi engineer diagnosed the problem & the remedy as: a new climate control unit @ £754; a new gearbox switch @ £287; and a new temp sensor & £135.

I am not convinced that this will solve the problem; and if all these parts are required. I fear that these may all be symptoms of some electrical problem and I might end up paying a lot more if these parts don’t solve the problem – similar to some ongoing expensive repairs that I have read from other forum members where half the car ends up being replaced!

So far I have done the following:

• Researched every known Audi forum for similar problems – which there doesn’t seem to be any evidence of.
• Checked the climate control unit for a live feed with a circuit tester – which seems to be there; and a good earth – which also seems to be there.
• Carefully inspected / twisted etc the wires & connecting blocks for poor connections / broken wires.
• Removed the unit & inspected the PCB for any signs of physical damage etc & re-soldered some of the larger terminal connecters to ensure there is good connectivity.
• Replaced the NEC dual relay on the PCB that is used for power circuits with one exactly the same – bought from America. But with no change.

My plan now is to try & buy replacement unit from ebay – which go from about £40 to about £130 – but getting the correct part number is proving to be difficult.

I am looking for part no: 4B0 820 043AQ

The ‘AG’ is the bit that seems to be different for different models & the one I need is for a double-sized standard DIN (which I now know means a double-sized radio unit) and without heated seat controls.

I don’t know why they all have different model numbers as they all look to be the same size (even the single DIN) ones and from the pics seen on ebay seem to have the same connections.

ETKA says these ‘AQ’ models were fitted to:
02–05 A6s; 00-05 A6 Allroads; 02-05 S6/Quattro; & 03-05 RS6s.

So if anyone has a spare one I would be interested.....

OR if anyone knows why a unit for single DIN & double DIN should be different – when they both look identical.

OR if they suspect any electrical problem that is causing the climate control problems or some of the other electrical problems – I would be grateful.

If the replacement does not work I will be looking for a good auto-electrician in the North Herts area – so if anyone knows one – please let me know.

Meanwhile I am struggling with no heater or demister!!!!

Any help or guidance is much appreciated.

John

[JohnHighfield]

Hi Forum readers.....

Just an update: I have now aquired a spare climate control unit off ebay & guess what? The exact same problem continues..........

So paying £100s for a new one would have been a complete waste of time & money!

So again - any help or advice on what now really seems to be an electriical supply problem. Is there any type of ECU etc that controls the power supply??

Regards - John

[JohnHighfield]

Well we finally got a resolution to the weird climate Control problem.

After paying Audi £120 for an hours diagnostic work with their diagnosis requiring a new climate control unit for £754 and a gear switch (as I was getting the PRNDS); and a oil temp sensor as it seemed to have gone dead – all adding up to a whopping £1000+ pounds……..

I checked the fuses & the relays & the wiring as best as I could and tried an ebay replacement climate control – but the same symptoms persisted ……..

I finally got back to my Audi / Seat / VW independent and…….

After an hours work tracing the wiring back found a defective fuse!!

It baffled them too, at first, at it looked good (as it did to me) but its connection was intermittent.

Apparently the Climate Control unit is a gateway & effects the supply to other circuits so.. Oil temp is now back up & the PRNDS was not showing – and may be corrected.

So Audi £1000+ Vs Mark Tempest Autocentre, WelwynGarden City - £64.04!!

No Contest!!

John

[biggs001]

WHAT A RESULT!!!!! excellent!

[AUDIDolley]

Can you advise which fuse was causing this issue I have a similar problem, thanks, Wayne.

[JohnHighfield]

Hi Wayne

I took the fuses out & looked at them & they all looked ok. I checked the handbook & made sure I checked all the ones that related to the climate control - but did not spot anything.

I even ebayed a spare unit; substituted it & found it to behave in the same way..... which was just as well as Audi diagnosed that I needed a new unit @ about £800.

I booked it into an Audi Indy for their electrician to check it out & he found that the fuse was intermittent - which I did not think was possible.

What I would advise you to do - if you think your problem is similar - is to buy a range of new (and therefore good) fuses and replace all of those that might have some effect. I am sorry but I can't remember which one it was.

Needless to say - its still working perfectly!

Good kuck with it - & get back if I can be of any further help.

John

[AUDIDolley]

So are you referring to the fuses found in the on the end of the dashboard with the drivers door open? I can find no other fuses.
Thanks for coming back to me, appreciated.

Wayne

[JohnHighfield]

Hi Wayne

Yes they are the ones. When it was intermittent I could hear clicking from the relays which are underneath the dash & behind the little shelf where the service manual can sit - below the steering wheel. I could also touch & feel them switching.

This initallly made me think that a relay was faulty - but they must have been in line with the fuse.

John

[nevo]

Remove the relevant fuses and check inside the fuse receptors with a strong magnifying glass,sometimes a hamfisted owner puts in a new fuse in and screws it up,also do a continuity test on your fuses,not visually.

[AUDIDolley]

OK thanks for your help I will do a continuity check on the fuses.
One point I have found is that on the back of the climate control panel I have checked for voltage on the 2 pin plug and I have 12v so does this rule out the issue with the fuses.
I def have the strange clicking but am struggling to locate where it is coming from sounds as if it may be from the speedo area. If I turn on the ignition turn it off and remove the keys it stops.

Any ideas.

The other strange thing is the front and rear fog lights are not working can this be related.

Thanks.



Wayne