How do I get the "Automatic Heater" system to work on the 85 Carrera?
 

Hi guys,

When I bought my '85 Carrera coupe the previous owner had headers on the car and had removed all the heater plumbing in the engine bay (the blower motor, air ducts, etc.). After I bought the car I swapped the headers out for stock heat exchangers, and yesterday re-installed all the original ducting, etc. So I'm trying to figure out how to run the heat in the car. I could have sworn somewhere in a box was those two levers that go down next to the e-brake, but for the life of me could not find them in his boxes of parts. So I looked in the owner's manual and it looks as though this car has the "Automatic" heater. The dial on the top of the e-brake goes like from 0 - 9. Also, the rubber cover that the e-brake fits through has no slots for those 2 little levers that I was expecting to have to install.

Anyhow, if this is an "Automatic" heat system, would it NOT have those two levers you lift up? And if that's true, how do I get the heat to work? When I turn on the dial on the top of the emergency brake console, I hear something hum, then stop after a while. (granted it's like 70 degrees here...maybe there is a thermostat?) The car was warm after driving, but not "hot", so maybe I just need to wait?? Could someone please enlighten me on how to use this type of heater?

Thanks guys.

As always, humbly - Mark.

Hi,
I've got an 85 coupe with the owner's manual and have yet to figure out exactly how to operate the heat. The manual is quite cryptic in it's explanation of lever position. Granted, I'm a noob. Some of the more experienced owners may be able to be of more help. That said, I do get very good heat with the top lever all the way to the left and the two bottom levers all the way to the right. The dial between the seats is the blower fan for the heat. Setting it to 1 gives me all the heat I need and I live in Colorado. My fan also makes the noise you describe for a few seconds. I think it's old age.

The system is.
a probe nipple behind the rear view mirror for the cabin temp
There is a probe in the flapper box on the left side
There is a bar in the box between the seats that needs the nylon end caps replaced. You have to pull the passanger seat to see the bar im talking about. There is a side cover on the control box. 999.168.021.40 Ball socket, 2 required
You need to clean the cable cover around the steel wire going to the flapper box on the inside to get the dirt holding up the cable movement.

Bruce

Argh.... It looks like the thermostat sensor up by the mirror is missing! I searched around for a part and it seems like they are not available anymore -- is that correct? What does this thing look like? Maybe I have it in my parts pile from the original owner.

Mark.

This is what I did:

http://forums.pelicanparts.com/porsche-911-technical-forum/647413-let-there-heat.html

If anyone could provide any data about the factory temp probe (specific electrical performance), it would be conceivable to develop a replacement. I'll continue to dig around too. I'd love to retain, restore, and/or improve the factory auto heat on my '84 Targa.

auto heat
 

On my 79Sc, my e-brake had 1 lever to the side that you were not to pull on ..it was automatic as the heat dial was turned...it lifted itself to the correct ht. My sensor was missing, the auto heat console dial just spun with no clicking meaning different settings. I either had heat or no heat. Found out the sensor was NLA so we changed out the e-brake componant with one that has the 2 handles/levers and then cabled back to the flapper boxes and now I have heat controllable by levers to both sides of the car. I do have 2 autoheat consoles...one that does not click and one that is new with harness if somebody needs them.

Agree. Not much experience in the subject but need the parts too. I'm ready to take another route, keep what I have as stock and for the missing temp sensor, perhaps try some other thermocoupler as a replacement. You can buy a fancy VOM with temp probes at HF Tools for $35 and I'm thinking of just using the included thermocoupler for the temp sensor. Thoughts anyone?

Auto heat sensor
 

Here's a parts list for the 1985 911 cars.

http://forums.pelicanparts.com/uploa...1325464286.jpg

Unfortunately, because Auto Heat was an expensive option, not may folks opted for the system, making this a very difficult part to locate.

http://forums.pelicanparts.com/uploa...1325464395.jpg

You may have to call salvage yards, or do a search "Auto Heat Deletion", "Used parts", as many members retrofited the system to manual.

Good luck,

Gerry

pm me as needed.

I found someone on the forum with a used sensor, but until that arrives I decided to take the advice of someone who responded and removed the side cover from the center console and operate the lever manually. After many gyrations of trying to free up the cables and flappers I got to where I could operate the flappers manuall from under the car pretty easily so I thought everything was freed up. Found out, however, you can't get enough mechanical advantage to easily overcome the return springs on the flappers by pushing that lever from inside the center console. It was all I could do to force the thing to move so I could close off the flappers.

Long story short, I jacked the car up again and removed the springs so I could move the lever easily. Now there is heat! I can operate it manually....but...(big but)...it's on all the time. Apparently w/out the return springs I can't get the flappers to fully open back up again. And holy cr@p is it HOT air coming out of those foot well and windshield vents!! So tomorrow I'm putting the springs back in place so that it will close by itself. Meanwhile have ordered new cables and cable guide tubes (which are pretty old and cracked on my car). My hope is once I get the sensor and the new cables I'll have a normal heating system. We shall see...

So on this idea of backdating the heat to manual -- can someone tell me if I can just buy a manual lever and install it into my center console, or is there more stuff I'd need to buy?? (maybe I should just do a search as was suggested and find out for myself...)

Mark.

Mark, I think you can replace the e-brake mechanism from a car that had manual heat. That was my plan B. 20th Street Auto would have them used or try someone on here who's parting a car.

Before you panic, make sure you don't have the sensor in the dash that replaced the one by the mirror, in 1986. Maybe they made the change late in the '85 model year production. Look for a round circle about the size of a quarter, with a couple horizontal slots in it, just left of the ventilation control panel on the dash.

JR

No levers on an '85. Earlier years might have had one lever.

There is a thermostat. If you pull the cover off of the right side of the control unit, you can use a mirror to see if the linkage is intact. If it moves, and is responsive to changes in the knob position, it's working.

JR

So on this idea of backdating the heat to manual -- can someone tell me if I can just buy a manual lever and install it into my center console, or is there more stuff I'd need to buy?? [/QUOTE]

You have to buy a lever (or two), plus a few other parts. It's easier to just buy a complete used handbrake assembly, with levers. If you choose to use two levers, you'll need different cables from the lever to the flapper boxes.

JR

The diagram you posted has labels that impliy that the coupe and targa/cabrio used different parts for the heat sensor. Actually, is a model year change. After 1986, they used the sensor in the dash, coupes included.

JR

The top lever all the way to the left closes the fresh air intake. At that point, the middle lever position doesn't matter, as it just directs where the fresh air goes. Left is to the footwells, right is to the dash. With the upper lever to the left, there's no fresh air admitted to the cabin to control.

Better heat is obtained with the lower lever to the left, as that puts the heated air into the footwells.

JR

Thanks for the tip, JR, but I looked up the diagrams and unfortunately mine should have the one above the mirror - there's no sensor in the dash. Actually, the P.O. left the wire hanging up there. Why on earth he didn't save that sendor, I'll never know... He was really good about everything else.

So if I can find a used manual setup with only one lever, I don't have to buy new cables? Or will I need different cables/sleeves anyways if I convert my automatic heat to manual setup? I'm just about to pull the trigger on ordering a new cable (dual cable) and 2 new cable sleeves (guides) for the automatic system.

I had a 85 Carrera years ago with the automatic hearing system. Even when it worked, it wasn't that great. The two lever system between the seats work far better, simpler and easier to adjust.

Great info all. I'm in the same boat and its beyond me why the sensor is gone. I have a feeling that once a blower or something obvious is bad, some tend to grab at the first thing they see... like above the mirror... yanked out. My blower was seized, which blew the fuse. Simply corrected that and and all is fuctioning except for the elusive sensor. The car I'm refering to is an early 84 and is the same as the 85. From memory, I think it changed late 86 for the 87 model year bigger vents and the sensor in the dash.

I came across the following data when trouble shooting the autoheat in my SC.

The Porsche Manual for the SC refers to the mirror sensor as being "1.5kOhm at room temperature". Bentley gives the value as 1.9k Ohm at 20C(69F).

The heat exchanger sensor is listed by Bentley at 1.7K Ohm at 20C (69F). The Porsche Manual lists the value for the exchanger sensor at 135 Ohm at 100C (212F).

It may be possible to find standard thermistors that are close to these values.

Thanks!! This is very valuable information. I'm sure it would be possible to find a stock thermistor somewhere that would give these same readings.

Mark.

Porsche has used single cable and dual cable systems at various times, so you could use either. The single cable actually uses the same guides as the dual cable, since you have to have a wire going to each flapper box. The difference is at the end where the cable(s) attach to the lever(s). I prefer two levers, as then the heat can be adjusted separately on either side. Note that several different wires have been used over the years, so buy the one(s) that is(are) for use with whatever controls you end up deciding to use.

Sorry to hear about the sensor. I figured it was a long shot but worth checking.

JR

The 1986 models had the revised sensor location and the bigger dash vents.

JR

Auto heater 197 930
 

After reading the posts today I tackled my inoperative auto heat this afternoon (Federal holiday). 40 degrees today in the MD/ DC area, so great for getting heat to work.

My passenger seat came out very easily, although watch for the backing pates to fall to the floor. I used a magnet want to fish them out. Turns out the clevis on the front end of the rod was broken. Broken because the cables were very stiff. I confirmed this by moving he cable belcarank manually. I was able to tie wrap the clevis end so that it stayed (mostly) on the ball stud long enough for the heat to come on while holding the clevis against the belcrank connected to the heater cables.

Next, I got the car up on a lift and sprayed some PB Blaster on the cable ends under the car and worked the cable back and forth some as best I could. I need to clean and or replace the cables, but at least I now know the auto heat unit is function. On the way home from the lift, auto heat worked, including the max "shoe melt" setting. I'm pretty sure the rod clevis will pop off again soon, so I'll get a couple of those too and leave teh right seat out for now.

Thanks to all for the advice.

Auto heat 1987 930
 

http://forums.pelicanparts.com/uploa...1325540678.jpg

Forgot to include a picture for reference. CV