Trouble shooting heater core valve question
 

Got the 968 to bleed and enjoying driving it. Last thing to fix is the heat.
When the knob is turned to hot it blows warm breifly, then cool. I have

1. Blown water through the heater core and know it is clear.

2. Hooked a vacumn gauge to the line at the valve. When knob is turned I get good vacumn for 2 or so seconds then nothing. Seems to match the interior heat experience.

3. When I manually push/pull the heater valve lever I cannot get good flow to the core either way so I was initially going to replace it. However when I bypassed it with the vaccumn gauge and got results I didn't understand and wonder if it could be something else.

Any ideas appreciated. I love this forum. So much help and experience.

Hi Shelby,

I am in the same boat as you but have not checked what you did, thanks for the tips. On the other hand, the 944 has an infamous little white plastic clip that can be found on the drivers side of the center console underneath the dash. That clip holds a metal bar in place that directs the heat. When this breaks, it can be the source of a no heat condition. I don't know if the 968 has this but it may be worth a shot since all else is great.

Good luck,

x2 Happened in every 944/968 ever made. Very common, very easy fix. just pasted the first google search

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

Actually, when the rod comes out of the clip (whether broken or just popped out) the heat will default to hot, hot, hot. This is by design in most german vehicles to keep the car operator from freezing in the winter. Check clarks garage for some good checks and proceedures.

The heater valve opens to let water flow when vacume is applied. From what you're describing, it sounds like you have a vacume leak in that system. Since you initially get vacume, I'd suspect the leak is between the water valve and the HVAC controller, but it really could be anywhere.
Start at the heater valve and work your way back to the intake manifold.