Unwanted hot air - How to fix. 83 sc

[on-ramp]

it's a 1983 911sc.

first of all the blower motor has never worked. I'm driving in 70 degree weather with hot air blowing from the side vents.

how do i stop this? the heating levers are all the way down. Any way to replumb the HVAC?

Thanks in advance.

[Joe Bob]

Sounds like the vents are rusted open off of the heat exchangers.

[randywebb]

open?

Get under the car and check the heater dump boxes with your heater lever down (that's the one between the seats). See if the vents are open or closed or part-way.

[Joe Bob]

Yeah...if they were rusted shut you wouldn't have ANY heat.

[diabolos88]

my 930 is having similar heating problem.
I have never ending heat on drivers side, the center heater control is turned off(down) to "0" and I still have heat. I disconnected the hose under the car that clamps onto the heat exchanger and the heat went away. Now what do I do from here?

[Todd Simpson]

Open? Closed?

It's kinda both.

The heater boxes under the rear seats are the problem. They always have heat coming in but they determine where it goes. With the heat off, there is an internal flap that closes inside the box and the outer pie plate shaped holes are open. That dumps the heat in front of the engine.

When the heat is on, the internal door opens and the outer pie plates close. The heat is then forced the make the long trip forward, first through the flexible hoses, the rockers then the dash controls.

To fix you'll most likely have to replace the box on the side you are having a problem. It's a real pain with the engine in place. The studs holding them in are very small, take great care not to snap them.

For a temporary fix disconnect the hoses or better yet just turn the box to the off position. (open pie plates) Maybe try adding another spring to pull the box closed, you might get another year out of them.

[CarreraDan]

Todd,
Are you saying that there are two flaps in the heater boxes--the pie ones on the bottom and another one? It would make sense considering I always have heat too, and my flapper boxes are wide open (pie shaped part that you can see). I guess next time I am under there I am going to have to take a closer look.

[diabolos88]

my heater boxes are also wide open, and I always have heat just on the drivers side. So this means the inner flap is either rusted off or has rusted open.
Prob good idea to replace both boxes.

[Todd Simpson]

Yep, there is a door inside the flapper box.

[CarreraDan]

Well, it looks like both flaps in each box are intact and working after getting under there and looking. I noticed there is a gasket around the edge of the flap on the inside so it must not be sealing anymore since I always get heat on the drivers side. I guess the next step will be replacing the boxes next time the engine and tranny are out--I don't think it could be done with them in b/c one fastner is hidden on the top. Also, they are nice and rusty--so they will most likely snap off.

[Jims5543]

I realized I have the same problem. No wonder this car gets so hot in the summer.

I did not want to disconnect mine because when I am in the mountains I am still using the heat at night and early in the morning.

I decided to climb under the dash and clog the hole with a rag that could easily be pulled out if I needed heat.

I just drove my 911 from North Carolina to Florida (I noticed the heat during this trip, I had flip flops on and my left foot was cooking) the heat was killing me on the way down. I did the rags in the vents trick for the return trip and it helped a lot. I hope this is safe. In the back of my mind I wondered if that would casue the exhaust to overheat.

There is still heat generating from the dash but now hot air is not blowing on me.

[randywebb]

There is some irony in stuffing a rag into one of the world's best designed semi-exotic sports/GT cars...