I don't want to speak out of turn, but I think this is an urban myth. With a few other Audi models of a similar generation it was possible to make the climate control unit go into a service mode that would return information otherwise only available through a reader / VCDS, but the one in the A2 does not have that facility and doesn't respond to the magic combination of key presses that would be effective in a 4B A6 (for instance). Do you have any other info (which engine, what other symptoms etc.)?