Porsche Repair: Blower fan heat control, coolant water, heater blower

Question
Hi, have a 944 (86) with later oval dash. No air con. Everything works fine with the controls except, I can't get anything but full heating. Within 5 mins the car is roasting! Can only find info on net relating to older style dash and mechanical heating controls. Any help on where to look, what to replace very much appreciated...

Answer
Hi Barry,

I'm not lucky enough to have a 944 here at home to look at and the reference manual I have doesn't cover what I'm looking for.

Here's the deal: some of the coolant water from the radiator/engine block is diverted to the passenger compartment area and when the heater blower motor is on the warm air warms your tootsies.  What I'm not clear on is whether the "diversion" of water is controlled by a valve (like a mercedes) or wheteher there is always hot water in the line.  Could you trace the water lines coming through the firewall...if there is a valve it'll most likely be attached to the firewall just before a hose goes through.  Thanks.

Dave