Hi - I would be grateful for any help in replacing my climate control unit: A6 2003 Avant 2.5 TDI 163 Sport. I have posted aspects of this problem before but now need some guidance on the compatability of replacing my defective unit with one from a breakers / salvage service etc as new from Audi I have been quoted £800..... My part no is: 4B0 820 043AQ & I have seen many on Ebay from about £40 upwards which look the same and have a similar number. 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.