86 climate control

[rbethell@mtroyal.ab.ca]

>From a new member of the list who is amazed at the amount of Audi help...

When on the highway, the climate control on my 86 quattro wagon, (230,000 kms)
sometimes sends cool air through the defroster and footwell vents even though
the temp is set at 24 degrees (Canadians use celcius), and the only way to get
hot air back is to play a lot with the blue & red temp buttons. And it sometimes
blows hot air through the dash vents.

I thought the dash vents were only for cool air, and defrost/footwell for
heating. Is this correct, and if so what needs to be fixed? The sensor? Control
unit? The coolant valve near the firewall?

Thanks
Ross Bethell