Compatability advice needed on changing the climate control unit

[JohnHighfield]

I have been having problems with what seems to be an an intermittent power supply to my climate control unit in my A6 Avant 2003 TDI Auto 163 Sport.

The unit turns off (with LED info in the windows going off); it momentarily flicks back on but tends to stay off after about 15mins of flicking on/off. When its on, which is briefly, it seems to work OK......

The outside temp on the drivers display also tends to disappear - after a while - and / or come up with erroneous readings....

Audi have diagnosed that I need a whole new control unit at £800 and my part no is: 4B0 820 043AQ.

I have seen ones for sale on Ebay & from salvage dealers which seem to look the same and the only difference being where mine has the 'AQ' they have a different alphabetical code - which may correspond to the year of the doner car.

I have found my way in to removing my unit & my question is -
a) will any these be a straight swap - or must I find one with the 'AQ'?
b) is there any requirement to code up the 'new' unit to the cars computer to overcome any ant-theft measures on this model?
c) if it does need re-coding I have read this is an Audi job - is this so?

Any help & guidance will be much appreciated as this is an ongoing problem - and its cold out there!!
John.

[paul b]

John,

Does your car have satnav (RNS-E probably) built in to the centre console? Or does it have a Concert or Symphony? This will help answer your A question.

B)- With VAG-COM or similar, record the softcoding number from the computer and recode the new one with the code you have written down. That's it.

C)- No, it can be done with someone who has a genuine VAG-COM interface, sadly mine won't do it as it is a 3rd party interface that suffers communication problems with climate control units.

All the best and happy new year.

Paul

[JohnHighfield]

Many thanks Paul B for getting back to me.

I don't have a sat nav unit; or heated seats & do have a symphony sound system.

looking at some of the units on offer (2nd hand on ebay) many say they are for a 98-2001 - so I assume there must have been a spec change then.

I also contacted a seller on ebay, who had one that looked identical, but he said it would only fit a 97/98 car... Alas not a 2003.

I too have a 3rd party Vag Com lead - but dont know how to read the soft coding for the climate control unit. Is it one of the blocks??

If I can get hold of someone with a full VCDS what should I be looking for & how do I put it in for a replacement unit - assuming I (can get one).

Sorry to ask so many questions but the problem I have does not seem to listed on any forums that I have searched.

Many thanks fror your help - John.

[paul b]

The difference between 98-01 versions and facelift is that the facelift ones are simply a slightly different shade of black. I have 1 of each at home.

As you have a Symphony sound system, I think you'll need a CC unit from a car that has a double-din factory fitted radio such as Symphony, or maybe one that has had sat nav will do.

Seen as you have VAG-COM and a lead/interface, you can try for yourself. I assume you have VAG-COM 409.1. Try reading the HVAC (climate control) controller module (if you can) and when you enter the controller you'll be confronted by your part number amongst other things in a number of fields. The softcoding will be mentioned in one of those fields on screen, you don't need to go into measuring blocks. Record the softcoding from your old unit, remove and install new one, then change the coding of the new one if necessary to what you have written down.

[JohnHighfield]

Thanks again Paul B. - John