What control from inside the car controls these? My car is an '86. Both vents on the flappers move when I work them from underneath, but I' am not sure which control actually pulls them closed from inside the cabin? I figured I would ask before pulling things apart. I assume the center **** between the seats controls them and when it is on 0 they are open and 9 closed. However, my **** does not close them.
Thanks
Doug

 

Doug,
The heat flappers are controlled by a servo motor located in the temperature control box between your seats. Generally what happens with these units, the control arm pops off the servo motor or on the other end where it mounts to the arm. Cheap fix and the arm is available from Porsche. There is an access panel on the side of the box where you can inspect to see if the arm is indeed off.

Dave
'85 Factory Slant 930

 

Doug,
I had to replace mine and it is not too difficult of a job. A couple of things to do to make it easier. One, remove the passenger seat and mark the spots where the bolts go through the seat rails. After you get the seat out put some glue on the four rectangluar nuts (flat metal plates with two holes each), that reside inside the floor rails and put the bolts back into the rails, through the plate nuts, and tighten them down to let the glue set up. When you go to replace the seat it will be a snap! If you don't glue the bolts into the rails it is real hard to slide the long nuts into the rails and thread the bolts through the seat frame and hit the holes while holding the nuts with your fingers with the seat in your way. Whew!
Two. There is an access cover plate but if the rear connector broke or came off, you will have to remove the four bolts that hold down the control box to get to the connector. The control rod is cheaply made with plastic hyme joints at each end and as the friction builds up in your flappers and cables they finally break. I replaced mine with Holley carburator joints that are made of brass. One other thing that I thought about doing was drilling a small hole at the front side of the control box, beside where the e-brake comes out of the box, in line with the control rod and attaching an additional rod to the rear connector so that the heated air can be manually controlled. I don't know about your controls but mine are from a **** torture room! It cycles from freezing to boiling and it does it randomly. The older cars had little levers instead and I think they might have been on to something.
There are several sensors around the cockpit that tell the temp controller what to do and when these start to fail or are improperly positioned or covered up the controller loses it's brain. There is also a two week college course on the fresh/heated air panel on the dash!!!
LOL,
Rudy

 

rudy,
Great writeup. The replacement "heim" joints you mention in your notes, have been redone by Porsche. They are made of a much stronger material than the earlier ones and should last a lifetime....of course for a Porsche, that's a l-o-o-o-n-g time!

Another point. while you are under the car looking at the flapper boxes, lubricate them with a high lubricant. The easier the cable moves, the less strain the servo puts on the linkage. Those lines will kink over time.....maybe replacing them would be a good idea?

Dave
'85 Factory Slant 930

 

Thanks
Didn't realize that they were electric servos. I put the car on a lift and started it. They don't fully close when it is on 9, but they will put out heat. After more research, I realized that there really is no fan that blows the hot air out, just the engine fan. RPM realted heat...how ingenious.

 

You can hook the carrera blows in the footwells like the 3.2 I drove mine in the winter this way and it would cause the metal eyelets on my shoes to burn my feet! Worked great and can be done cheap. Those motors cost nothing out of a junk yard.

 

Stephen,
Can you provide more info on adding the footwell blowers? I have a 76 that I want to do this to. I have been reading other posts and they have all talked about removing the engine blower and burning out the footwell blowers. I have auto air that I have replaced with a newer unit. It works well but it wout be nice to have a forced air defroster on the cold nights.
Thanks in advanced for any info you can provide.
Bill

 

On all my old cars I would pick up a set of used motors. There are some special hoses that fit in the foot well on the lower side. I can give you that number. You will need to get those from Porsche. Then simply pull the carpet pack just in front of the door and pull the original paper air duct. Cut the top half off and place the motor and sleeve in place. Then all you need is a resisted switch or potentiometer to control the motor for speed and that’s it. You don’t have to do a variable switch, but it will get to hot. You will suffer from “oh lord I am cooking” to “ I am freezing my toosh off!” The variable speed makes it just right Works like a charm..

 

.....and don't forget to fuse the motors! Don't ask me how I know this.

 

If you get the newer motors they should have the fuse built in. If not YOU DO need to fuse it. They, ummm would cause a better warming soultion

 

Stephen,
Thanks for the reply. I have the blower motors and, if the additional part under the motors are short rubber elbows, I have them. I am trying to control them through the auto heat console. I know only enough about wiring to hurt my self. I bought this car in 79 with 20k on it have put over 300k on it since. I have done all the maintence myself, and while I know it very well, I have not even sat in another Porsche. I want to have the temp dial control the blowers and not add another switch. There are three switches in the control unit that turn turn on the blower at different levels. These switches are turned on and off by the moving wheel in the control unit. The same wheel that pulls up the lever that opens and closes the heat vents in the rear. Full on (9) runs the power trough a fused relay to give full force. The other two swithces run the power through a resistor assembly. This is the part that I am looking for. I think the resistor assembly has two levels. I have found a document that says the levls are .85 and 2.3 ohms. I have located a porsche assembly that has a 2.5 and .75 ohm connection( that is what is printed on the unit). I think it was used to control the air conditioning fan and located in the air inlet in the footwell to the evaporator. I do not know how to post pictures or I would post them of the unit and the wiring diagrams. I could not find where I got them from either.

I guess what this leads to is, can the unit made to control the lower speeds be found and if not where is a good place to mount this one that I have, that will not affect anything else with the heat it will generate?

I will try to email you the pictures because I can't seem to post pictures.

Thanks for you help.

 

Yes it can. There are several potentiometers available. You will want to order one that was for an auto heat Carrera. There are several options. The key to making it work properly is making sure that the reference sensors are the correct one for the switch. They use the resistance created at a given temp both at the flapper valve and in the interior to relate to the switch. So 2.3 ohms represents a specific temp. As the sensor cross references the flapper sensor and gets closer to the targeted 2.3 ohms as selected on the switch the servo comes down. Slowing the fans and lowering the flaps. It constantly regulates what ever resistance has been selected. The resistance is your 1-10 on the switch. So what ever you do make sure that these three components are from the same car.

You can simplify it by using the output to the servo motor to control the fans. You ideally would have three relays resisted out to create a certan speed on the fans. As the servo comes down being controlled by the out put it would trip the relay at that given sweep and allow a different speed to some down.

If you are really handy with electronics a simple 555 Timer and a series of op amps to compare resistance would also achieve the same thing, just in a different form.

 

See what I mean about the two little levers by the Ebrake handle? They are a work of genius!
Rudy