Electronic climate control playing up

[Dag Bøsterud]

I have a very late 1990 Audi 100 Turbo Quattro Sport Exklusiv on which the climate control has started playing up.
The problem seems to be that the climate control system seems to believe that the temperature in the car is lower
than it actually is, thus always blowing hot air. If I set the system to LO, it blows cold, because the system doesn't
care about input from sensors when in LO. Since my car is a very late 90's, the dreaded bowden-wire is gone,
and my climate control system uses the same temperature control motor as the new climate control system
that came out for the Audi 100/S4 (C4-cars) in 1991 and the V8 in 1992.
This time, the little motor is not at fault :)

I've done a bit of fault finding using the systems fault diagnostics, and it seems that the sensor mounted on the roof
is somehow giving the wrong values, although with an ohm-meter it measures okay - at least according to the Bentley
manual.

So.. any hints, tips or clues?

/Dag
Norway

'90 100 TQ Sport Exclusiv
131 000 miles

www.little-e.com/vinter