I know youve probably seen this problem before but...my car has just recently been blowing only hot air, especially at higher speeds/revs like on the freeway.Even when the vents are shut and theair is off, hot air still seeps in! SoI talked briefly w/ a friend at Brumos (local Porsche Dealership) and it may be a plastic clip on the heater control unit (He gave me a small plastic plug/clip).Just wondering where it is and if there are any other possible problem areas...Thanks in advance!
~James

 

Look down on the side of the unit (drivers side footwell)

 

Thank ya kindly Doc! Hopefully that will fix it...

 

when you say plastic clip are you talking about the tempature potentiometer that controls wether it blows hot or cold air? I'm having the same problem but I just need a new heater valve.

 

Yeah thats exactly what I was talking about...sadly that didnt fix it so I guess it could be the heater valve or something else...

 

Check to make sure the vacuum line is connected to the heater control valve and the firewall.

 

I ahve the same problem...waht happened to the other thread?