Rear hump connectors

[TroyGT]

My heater blower quit working and I've been tracing some wires. The PO of my car had wired something odd from the heater control knobs between the seat... I pulled up the rear carpet and found two separate plugs. Can you tell me what these are for? The bundle of wires from one plug travels down into the gear linkage compartment on the hump in the back.

This all started by following an odd red wire hooked to my heater fan in the engine compartment, out and under the car, then back into the rear seat compartment. It traveled under the carpet and connected to a spade connector on the front of the heater control levers. PO had cut the yellow wire on the heater fan plug and ran this red one instead.

Thanks

-Troy
86 Carrera

[TroyGT]

Maybe I made the question a little murky... let's try again. On the rear floor hump under the carpet and in front of the shift linkage access panel there are two electrical plugs. Can anyone tell me what they go to?

Thanks

-Troy

[slodave]

Can you post any pictures?

Dave

[TroyGT]

Okay, here's a picture of the connectors that I'm referring to. They are on the middle rear hump, under the carpet, in front of the linkage access panel. From what I've read, I think the two yellow wires from the left plug go to the heater gears between the seats. The rest were cut by the PO and I've haven't a clue where they should be connected now. Any help would be appreciated.

Thanks.

[TroyGT]

C'mon folks, surely there's someone out there who has removed their rear carpet and noticed these plugs. Left side plug has 2 yellows, a brown, and a black/red wire. I can't figure out how they should be re-connected.

-Troy
86 Carrera

[Super_Dave_D]

OK I hope this helps

From left to right

The first arrow are the connectors your talking about (covered)

The second arrow (yellow wire) connect to the lower front of the heater levers themselves. (they are connected in the picture)

The third wire (blue I think) is for the little heater control light thats between the seats

The other plug (covered) connects to the heater control module.

sorry not the best pic - it was from a month ago - not taken for your question.

[TroyGT]

Thanks David, that's helps a bit. I have the two yellow wires connected to the heater levers, like you do... so I guess those are right. There's still the red/black and the brown on that left plug that I don't where to connect. The wires coming off the right plug were cut about six inches off the plug and I have no idea where they lead or how they are connected. Anyone have a shot of their plugs without that cardboard cover on them. I'd love to see where those wires lead to.

Thanks

-Troy

[Super_Dave_D]

Does your car have the automatic heating system? Theres sensor to the left of fresh air /heat controls on the dash if you do? If so maybe those wires are for the Auto Heat System? The Bentley manual references this on 801-3 but my car doesnt have this option.

[TroyGT]

No, my car doesn't either. I just have the manual heat levers and a handful of cut wires that I have no idea where to connect. I skimmed the manuals and I didn't see anything obvious. I've also looked at the electrical diagrams, which is where I found that the two yellow wires connect to the levers. But, I'm no electrician and those diagrams are challenging for me. Thanks for you help though. Everything is appreciated.

-Troy
86 Carrera

[TroyGT]

These kinds of things are really aggravating. If the PO wanted to unhook all those wires, fine, all he had to do was unplug them and leave the original harness in place. Instead, six inches past the final plug.. he cuts them all in the same place. Now I have this mess to contend with. Whoever gets my car when I sell it will definitely never have this kind of problem to deal with from me. I lose sleep over this kind of thing

-Troy

[TroyGT]

Last bump and I give

[Mysterytrain]

no, don't give up.....An 86 carrera should have footwell blowers installed. Even if you have the manual heat version there should be a heater control box that sits between the seats. The manual console had a 3 speed switch on it that controlled the footwell blower speeds.
The brown wire is ground.
The Black/red wire might be the 12 volt feed from the engine compartment fuse panel.
It looks like some removed the additional wiring. I love hackers!

This is a very simplified schematic of the manual heat circuit.



On the right side of the drawing you will see the brown ground wire. The wire on the far right that goes from pin 4 of the engine compartment controller provides 12 volts to the heater control console..I believe that is the blk/red wire entering the left connector in the picture you provided. The yellow wires are indeed from the two levers on the sides of the handbrake and provide a ground connection that turns on the rear engine compartment controller. More about that later.
Ok, back to your picture...the connector on the right is the connector that goes to the heater console switch that should be between your seats. If its a manual heater unit then the wiring should be as follows.
Black/Blue - instrument lights [for the little light in the console]
Brown - Ground
Black - power for the three speed switch
White - footwell blower slow speed [position 1 on the switch in the above drawing.]
White/Black - medium footwell blower speed [position 2 on the switch in the above drawing]
Brown/white - switch ground for the high speed fan relay [position 3 on the above drawing.}

The carrera had an interesting manual heating system that I will attempt to explain.
When you pull up on the levers you power up the engine compartment controller and open the heater dampers that allow hot air to enter the car. The carrera had 3 blowers for the heating system. The rear blower and blowers in each of the footwells. In addition there are two heat sensors, one on the heater damper and one on the top of the engine. When the engine compartment controller sensed that the heated air was hot enough it would turn on the rear blower. Once the rear blower was operating the logic circuits in the engine compartment controller allowed the footwells to operate at anyone of the speeds that you selected. If the engine compartment blower failed..the footwell blowers would not work.
Additionally, there were a couple of other quirks. The engine compartment controller was tied to the speedometer and that sensor on the top of the engine. If the car was not moving [ie: stuck in traffic] and the sensor on the top of the engine got hot enough, the engine compartment blower would come on and force some air thru the heat exchangers to help move heat away from the engine. Cute!

Here is a schematic for the automatic system but it also shows the circuits that are not used in the manual system.




As you can see there a few places where a component failure would cause the entire system to stop operating. Fortunately, the system can be broken down into sub groups to make troubleshooting less of a nightmare. There are also work arounds to run the system without a rear blower.
lots of info here:
Help! Does anyone understand the footwell blower circuit?

So its you turn...tell us what is left in your car?
PARTS:




19 is the console that should be between the seats
1 and 2 are the footwell blower located behind the carpeted tumors under the dash.

[TroyGT]

My god Ron, fantastic information! Thank you so much for providing all the diagrams and the detailed explanations. I assure you that it is all much appreciated.

Okay.. as for parts. #19 doesn't exist in my car. I have rubber emergency brake boot that covers this entire area. It has slots for the heater levers and an opening to allow the emergency brake handle to pass through. I've never noticed a night light of any kind down there.

I have two footwell blowers that I thought were being controlled by the fan controls in the lower dash console... I have AC temp and fan speed dials on this console. I have a temp sensor of some sort in the dash behind a silver dollar sized grill. I replaced the temp sensor in the engine compartment in the spring.. so it should be fine.

The rear blower has worked before.. but started blowing fuses, so I pulled up the carpet to see if I had a short anywhere. Sure enough, I find all these cut wires. The red/black wire was wired to the heater levers... which appears to be incorrect. Another, totally separate, wire had been run from one of the two heater levers, all the way back to the to the blower in the engine compartment. The plug on the back of the blower had two wires on it, the PO had cut one, and then connected the long wire ran from the heater levers. Makes no sense to me.

So, first thing I did was get rid of the long wire from levers to blower and then re-attached the like colored wire the PO had cut... re-attached the plug. Everything should be fine there now. On the inside, I just have to go through the diagrams and the information you posted and try to get everything re-connected again.

I'm reading and printing out everything you sent. Again, thanks so much for the effort. You gave me tons of info to work from.

Thanks

-Troy
86 Carrera

[Mysterytrain]

Troy..you are very welcome.
I'm hoping that a carrera owner will chime in here..but I don't think your car came without the heater console pictured below. They are available from time to time on ebay. I installed a console in my SC last winter so I have pictures to share of the manual unit and some understanding on how it works.

Here is a stolen picture of the Console:



My switch in side the console:



My Switch connector:



Porsche used the red levers to activate the 'rear engine controller' which is nothing more then a couple of relays and logic circuits. The three speed switch in the console uses three micro switches to control the 3 fan speeds. Slow and medium speeds [ the two grey microswitches in the picture] are tied to a circuit that includes a ceramic resistor that is located in the trunk, behind the glove box area. These switches direct 12 volts to the resistor network and the voltage drop provides the slow and medium speeds. The high speed circuit is interesting. Because of the high current draw of the two footwell motors the factory used a relay to switch power to the blowers. That aux blower relay is also located in the trunk and its power source is from the front fuse panel. The aux blower relay is activated by the third microswitch [small black one] in the heater console..which provides a ground for the relay solenoid..note the brown and the brown/white wires.
So, your system should include the following, all of which need to be checked out:
1. A pair of footwell blowers
2. A ceramic resistor
3. Engine compartment controller
4. center heater console
5. Front aux relay
Additionally, the footwell blowers need to be fused. The factory at some point installed 10 amp inline fuses to prevent fires. Another change in the circuit also occured around the same time as the addition of the inline fuses and that was the elimination of the footwell blowers actually being off when the speed switch was in the zero position. Two reasons for that..the stationary fan blocked the heated air flow and secondly the heated air was so hot it cooked the blower bearings.

[TroyGT]

Wow... I really am missing alot then... an entire center console. No wonder things never made any sense when people described heating issues. That would also explain why I have a bunch of cut wires that have no where to go... some goober PO removed the console.

Just to be sure... Carrera guys... do all of you have a hard heater console between your seats at the emergency brake? Mine has nothing here but a rubber boot to cover the brake and heater levers. Ron thinks I'm missing this, but isn't 100% sure.

Thanks all.

-Troy
86 Carrera

[jester911]

Yes my 86 has the heater console. My car has the auto heat so no levers but still has the temp dial on the same little console.

[masraum]

I don't know, but when I saw the title of this thread I was expecting something more OT.

[Mysterytrain]

That would be the grid girl thread

[TroyGT]

Okay Ron, I bought a really nice heater console from Jeff (C U L8R) and it plugs in perfectly into my cut wiring... wire colors match and everything. Pulled up the carpet and the 4 mounting holes align perfectly with the console. Now, here's the thing. When I get it in place, the emergency break is fine, but the heater levers have no clearance and hit the console. I can barely even actuate them. So, I still have a problem of some sort. Any ideas? Are the heater levers different angled or different height between some 911's?

Here's a picture:

[TroyGT]

Oh my... I just noticed the difference. In the hi-jacked image you posted earlier in the thread, the emergency brake handle splits the heater levers... on mine, the heater levers are both on the right-hand side of the emergency brake handle. Crap... what has my PO done, retrofitted an older 911 heater lever assembly?

-Troy
86 Carrera