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Drowned climate control??

Discussion in 'Air Conditioning' started by John C, Dec 3, 2009.

  1. John C
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    John C Member

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    Hi all - I would be grateful with any help with this recent climate control problem.

    I have an Avant 2003 A6 2.5 TDI 163 Auto Sport.

    It started last night during a very heavy rainfall & as I was driving through lots of puddles & surface water - which may OR may not be connected....

    I first noticed the exterior temperature missing from the information system on the dash; then noticed that although the switches on the climate control unit were illuminated all the windows that have LED readouts were blank.

    The readouts occassionally flashed on (the external temp display sporadically displays random temps ie -47F & then reverts to +4C & then goes off again) but it failed to stay on & eventually stayed off.

    This morning after all the rain has ceased....it seemerd OK - GREAT, & was working again, on starting off - but soon started to flash on & off; and then eventually went off complertely.

    Needless to say = no heating / de-misting etc.

    I have a cheap vag-com cable & will try to take a reading over the weekend - although I am not sure what to look for, but in the meantime can anyone show any light on this??

    I have driven in heavy rain before without any probs but can the rain get into the control unit? Does it have an ECU? Are there any known problem?

    I had my previous A6 TDI for 7 years without any air-con problems....

    John
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  2. Staz
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    Staz is a retronaut Staff Member Moderator

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    I don't think this is an air-con fault per se but simply an electronic failure that happens to be in the climate control system.

    Any fault codes found with VCDS would help but I would suspect you're going to have to take it to Audi to look at :shrug:
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  3. John C
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    John C Member

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    Thanks Staz
    Strangely enough in driving it today as it went dead & the display disapperared it gave a clicking sound - which sounded like a relay switching - but in the area of the central column rather than under the steering wheel where I believe the relays are.

    I popped into Audi to see if they had a relay as part in that assembly and they didn't. They did however suggest that I booked it in to be looked at - which may be inevitable.....

    I also sensed that the clicking on & off seemerd to coincide with road bumps etc so a bad connection may be the problerm.

    How easy is it to remove / gain access to the air con unit? Again any advice / pics / other threads would be appreciated.

    John
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  4. Staz
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    Staz is a retronaut Staff Member Moderator

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    Yeah loose connection sounds very likely. I really don't know about A6s mate so I can't help you there. You'd be best posting in the A6 forum for advice on that TBH.
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  5. John C
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    John C Member

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    A6 Avant 2.5 TDI Auto 163 Sport

    Just paid Aidi £120.75 - the minimum booking of 1 hour - to Audi to diagnose my problem.

    A bad connection I thought as the power supply is imtermittent & seems it to flash on in relation to road bumps etc.......

    £754.97 for a new control unit - simple as that!!

    It would seem that the whole unit that IS part of the central console is required. I declined NOT to have this done through disbelief.

    Does anyone know a good auto electrician in the North Herts are that can actually look at circuits & repair / replace the defective parts - rather than replacing whole units???

    Plan B would be to try & pick up a used unit......

    I would be grateful for any advice or guidance on how to get into the air-con unit to inspect it myself - OR a good electrician OR the source of a good spare Air-con control unit - should I ultimately need one.

    Thanks - John C
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  6. Staz
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    Staz is a retronaut Staff Member Moderator

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    Woah that's steep! A used unit might be your best bet.

    You should send S8Craig a PM and ask for any advice on removing the unit as he does sat nav retrofits.
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  7. s8craig
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    s8craig Active Member

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    It just pushes out of the center console on the A3/A4, not sure about the A6 as I've never removed one yet.

    Just checked ELSA and it says to remove the radio, remove the trim around the heater controls and there are 4x 8mm bolts that hold the AC control unit in place.

    That's about all I know on the A6 C5 chassis.
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  8. John C
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    John C Member

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    Update - I have posted aspects of this problem under:
    - Drowned climate control
    - Help in replacing climate control
    - How to remove climate control??

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

    Reminder 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 is now intermittent as the unit switches on/off repeatedly (when 'on' it seems to perform ok) but only stays 'on' for a few minutes at a time.

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

    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; and then sometimes returns to read a 'normal' temperature.
    • 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 at all.
    An Audi engineer diagnosed the problem & the remedy as: a new climate control unit required @ £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 really required. I fear that these may all be symptoms of some other 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 the wires & connecting blocks for poor connections / broken wires. The on/offs dont seem to be connected to any manipulation of the unit or 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 – But with no change.
    I have now tried everything in my ability & my understanding....

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

    an 'AG' looks like it also fits as does 'AP' and 'AH' although these have heated seat controls thai I dont really need.

    So if anyone has a spare one I would be interested - to buy - OR even to borrow to see if it works.

    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
    Last edited: Jan 10, 2010
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  9. John C
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    John C Member

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    Just an update.......
    I swapped the climate control unit over today with one from ebay & guess what?? The same problem persists so its a good job I didn't pay Audi £750 for this!!!

    Of course it too could be defective in the same way............So my problem persists & I am still looking for some help & guidance to solve this problem.

    What controls the supply voltage to the unit? Is there an ECU / relay system etc that could be the problem? Any circuit diagram or advice would be appreciated.

    John
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  10. Staz
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    Staz is a retronaut Staff Member Moderator

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    Really sorry you haven't solved it John. I'll do some digging and get back to you when I can if I find anything.
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  11. John C
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    John C Member

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    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!!

    Thanks for all the help & interest - John C
    Last edited: Feb 3, 2010
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  12. Staz
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    Staz is a retronaut Staff Member Moderator

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    Sorry I never got back to you John but I'm pretty sure I couldn't have helped lol

    Very glad you got it sorted :yes:
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  13. nickj2403
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    nickj2403 New Member

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    Hi, not sure if I can get help here. My climate control unit is not working on my 2003 A6, I have no outside temparature display and it says my Oil pressure sensor is faulty. This sounds very similar to the problems above. I have checked the fuse for the climate control and it looks OK. But on reading this thread I am not so sure. Do you know which fuse was faulty so I can replace it and hopefully save myself a large fee from Audi. Thanks
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