Can somebody tell me how the heater lever controls the flapper boxes? Is it just one cable going throught the tube through the fire wall? Does it attach to another cable that hooks to both flapper boxes? I searched the pet diagrams, bird site, and haynes manual but can't find any info. Bird sells a cable and barrel nut for it but I don't know where the cable hooks on to. This is for a 1972 914 by the way.

I recently hookrd mine up so I think I can remember;
Hook up this one first - For heat, the cable from the red knob dash lever goes to the drivers box and opens the flapper that lets the air from the rear come into the box (outside air hose connection). On the same box lever that you hook this cable to, another cable attaches and goes straight over to the passenger box to operate the same flapper on that box.
The blue defroster lever cable connects to the other lever connection on the drivers box and operates the flapper the lets air go up to the defroster vents. When this flapper is closed the hot air is forced down thru the grille into the cabin. This box lever also has a second cable which goes straight accross, like the other one and connects to the same flapper on the passenger air box.
The top lever that operates the fan connects to the center box and opens its flapper to let fresh air in thru the grille in front of the windshield.
I think this is pretty close and should at least help you figure it out. I think the two straight cables that hook the drivers box to the passenger box connect to the lower connections on the drivers box. The clips that hold the cables on are a real bear to attach. It would be unusual if you didn't break a couple.
So to answer you question, I think 3 cables go thru the firewall.
If I messed this up, I'm sure I'll get corrected.

Nope. I think that you are referring to the fresh air blower, and he is asking about the heater flappers. The cable for the heater flappers is a big U shape. It has the handle in the middle, and the two flapper boxes at either end.

Pull the handle and it opens both flappers boxes.

it's one cable run in a big loop. goes from one flapper box to the lever and back to the other flapper box.
the lever has a hole where you need to fiddle the cable through.

pain in the butt to route that through, but works very well if installed right ...
Andy

Cool! I found a new one in a bag from the po. Didn't know what is was. Thought it was too long for the flapper box(es). The loop thing through the switch hole makes it all work out. You guys are GOOD!
Buck

Well I think I found one from the po. What does this cable look like? The one I have is about 7 ft. long.It has a threaded end on one side and a metal barrel on the other about 2-3mm thick. The barrel end will slip through the heater lever hole. There is a black sheath around the cable that is about 3 ft long with the one end being threaded with a nut. If this is it then how does it work?

The cable has no sheath. It is just bare wire with metal ends where the barrel nuts clamp.


That almost sounds like a throttle cable.

sounds VERY similiar to a throttle cable