Back dating heating system

kevin-ct · 07-01-2012, 04:55 PM

Hi All,

I have a 84 911 with the automatic heating system that is not working, what i would like to do is remove it and install a maulel set up with the two red levers.

So, the question is what will it take to install the older manual system? Do
I just buy the center center console with the rotary switch and the E-brake handle with the red levers and cables?

Thanks,

Kevin

dipso · 07-01-2012, 06:46 PM

You mean manual set up, not maulel set up, right? I don't know anything about an 84, but the way a backdated system works,is.
There are no fans or pumps anywhere. You change the heater blower flanges in the engine compartment and the cooling fan forces the heat through your exchangers and into the cabin.
This is controlled by the 2 red levers near the e brake.
But also and probably pretty important. Is on an older car there is a dash control system which directs the air/heat flow, to the windshield, dash or feet.

I don't understand what the center console with a rotary switch would be for.
There shouldn't be any switches and I don't think a knob would be enough to move the cables for direction.
If you have the heater control panel in the dash, I don't think you would need the console.
The red levers and cables just open and close the vents on the heater exchange boxes.

Like I said, i don't know anything about an 84, but i am sure if you do a search you can find out more information.
You may have to lose the console.

Porchcar guy · Porchcar guy's Garage

My 79SC had auto heat and it sucked..either on or off with no control. We replaced the E-brake assembly with one that had the levers on both sides and had to replace the cables and the heater boxes as they were rusted out. Works great now. The console with the rotory dial was taken out .

Elombard · 07-02-2012, 03:01 AM

The center rotary dial runs the foot well blowers I think. You dont need those either, just the levers next to the hand brake. Your dash control system might be different? I wonder if you looked at the PET diagrams if you could figure it all out?

kevin-ct · 07-02-2012, 04:05 PM

Thanks for the info.

I'll change out the center console and E-brake and cables.

Kevin

Mysterytrain · 07-03-2012, 03:02 AM

Kevin,
There are a few components to look at on your exisiting system that could make it nonfunctional. The engine compartment blower needs to be working to allow the inside footwell blowers to operate. This is the most common failure so it might be something to look at. Lots of info here:
Help! Does anyone understand the footwell blower circuit?
I backdated the heating system on my 78SC with SSI heat exchangers,removal of the rear blower and installed footwell blowers. I have tons of heat now. Here is the thread:
How to Install footwell blowers in pre -84 911's
There is info on changing the handle brake lever to one with the red heat levers on either side of the hand brake that might be useful to you.
If your footwell blowers are working you could modify your system to function the way mine does.

javadog · 07-03-2012, 05:44 AM

You don't need the center console with the 3 position fan switch if you don't intend to keep an auxiliary fan in the engine compartment, or install footwell blowers in your car.

You don't need to change the entire handbrake assembly, just the parts associated with the levers. A little time studying the Porsche parts fiche will pay off here. It may be cheaper to buy a used handbrake assembly, though. You will have to change the cable that's in your car to the dual cables needed for the older system.

JR