another dumb question, im full of them

[remi_357]

what exactlly controls the doors for the heat and ac? mine move very sluggish and most of the time stick open. any ideas?

[Smartin]

It's a combination of cables and vacuum diaphragms. The actual heater door is moved by the lower control (temperature) cable. All the A/C, defog, deice, etc are vacuum controlled.

[remi_357]

is there one main piece that controls the vacumn pressure? everything works just very slowly and the doors like to stick in the open position. just tring to figure out where to start digging in at

[73 Centurion]

On the engine side of your firewall there is a black plastic disk with domed sides. It has a bunch of vacuum lines attached to it. The vacuum for the heating and air conditioning doors comes from here.

I recommend you replace all of the vacuum hoses and T's around this black disk. A leak in a hose, or a small crack in one of the T's will release the vacuum before it can do the work of moving the doors. These are common problem and relatively easy to replace.

If that doesn't fix the problem I recommend you look at the doors on the system and make sure they move smoothely. If you can borrow a vacuum pump connect a hose to the diaphram that moves the doors and see if it works with a good source of vacuum. A hand pumped vacuum pump is a great tool to have.

Check each of the doors, they all should work easily and they should hold vacuum. Replace any that don't pass the test.

The dash controls have a circular disk that looks a bit like an octopus. It connects the vacuum source to various hoses that move the doors. This can be a pain to get at so save it for last.

Good Luck,

John

[remi_357]

great advice exactly the info i was looking for thanks