'74 Flappy Heater Box Stuck Open
 

Last year, I accidentally pulled the defrost instead of the throttle lever, and the box is stuck open. It sends hot air to my feet and lower legs and makes driving for more than 30 minutes hell on feet. Unfortunately, I also forgot how to fix this..:confused:

I'm not looking to replace them yet, just want to close the valve or flappy thing shut to stop the molten air from getting in the cabin. How exactly do I do this? Where is the valve located in the rear? And is there one or two?

Yes, it is under the car in the rear next to wheel wells. Most likely Orange flex heater tubes going into it.

You need to raise the car safely to gain access. Get some penetrating lube and spray the pivot points to break it loose and close it manually if wire is snapped.

There are two. Flaps will appear to be close, which mean open to the heat exchangers. You want to OPEN the vents so it will close off the tube going towards your cab.

Karl--call me if you need help with this. SmileWavy

Good info here

http://forums.pelicanparts.com/porsche-911-technical-forum/665472-unwanted-heat.html