Heating question /problem
 

I'm currently experiencing a heating challenge from my 85.5 944. Once the car is warmed up ( heater is working properly off and on) the cabin air flow is fine ( heater in off position) however after driving a while (20 minutes or so) the air flow starts blowing hot air. I have checked all the vacuum lines and the heater control arm is functioning properly. Has anyone else experienced this issue and if so what steps were taken to correct the problem?

Thanks for the help.
Bob

Which heater control arm are you referrring to? The one under the dash or under the hood?

Here is the first thing I would check...

http://www.kronowit.com/porsches/944-heater-fix.html

If that's not it, I would replace the heater control valve especially if it's not working because it dumps coolant too close to the clutch area. Some have moved theirs up to the front of the engine and I think that's a good idea although I haven't done it myself.

It's a simple system really and not much else could cause that. The heater control valve determines whether hot water goes under the dash or not and if it does, then the flaps in the ducting determine how much air comes in.

Hello,

There is also a small plastic clip that goes on the heater controls under the dash, and when that breaks the hot air will move ever so slightly at times into the cabin even when all else is off.

Normaly it is a function of the cabin climate control to have air moving in the cabin at all times to cut down on fogging the windows and other things - sometimes when the air can be felt as hot it is the plastic clip - cheep easy fix.

Thank you for your help.