Auto heat Wiring

[Burkie61]

Since purchasing my 83 930, my autoheat system has never worked - surprise surprise. I am presently in the middle of replacing my carpets. When I pulled my autoheat control unit, the wires were disconnected. I am now reassembling everything. I have found where all the plugs/wires go except two grey ones with bare ends that run from the back of the unit.

Anyone able to tell me where they connect? Not exactly a tech wizard. In other words, don't sent schematics cause Burkie don't do schematics.

Thanks

[Burkie61]

[86 911 Targa]

Originally Posted by Burkie61

Paul,

Could you please post a pic of the top side of this unit,
and give us more info. No heat?, no fans? ect...

I could not find any grey wires in either my '86 Bentley or factory manual.

If similar to our '86, possibly to your temperature sensor located to the left of the controls,
or the heater control unit on the left side of the engine compartment.

You may pm me.

Good luck,

Gerry

[86 911 Targa]

Originally Posted by 86 911 Targa

Paul,

Could you please post a pic of the top side of this unit.

I could not find any grey wires in either my '86 Bentley or factory manual.

Possibly to your temperature sensor located to the left of the controls,
or the heater control unit on the left side of the engine compartment.

You may pm me.

Good luck,

Gerry

[Burkie61]

Thanks Gerry

I will take a look to see if that is the one. My unit looks the same as the one in the diagram you posted. But I will post a photo once I have an opportunity.

Thanks

Paul

[Burkie61]

Here is a photo of my controller. Anyone else have any suggestions? Will try to check out the sensor Gerry suggested once I have time.

Thanks

[86 911 Targa]

Originally Posted by Burkie61

Here is a photo of my controller. Anyone else have any suggestions? Will try to check out the sensor Gerry suggested once I have time.

Thanks

Paul,

Do you have the 10 position, or the 4 position switch?

I need to see a top view with the cover off.

Also, symptoms as requested.

Gerry

[Burkie61]

So Gerry (thanks very much Gerry) and I worked our way through my problem and discovered some very important details:

First, the grey wires I believe were the power wires for a car phone that a previous owner had installed in the unit. It appears they mounted it on the top of the controller and spliced into the power in the controller to give it juice. And thus the littles holes in the top of my controller.

Second, when I went to locate the temperature sensor between my visors I found a hole in my headliner and two screws holding nothing but air.....so if you have an extra temp sensor laying around, I am in the market.

Fuses appear okay (visually and multi-metre tested). But no power to the Controller. So few things to work out yet.

[Jajohnsen]

Hi, hope it is ok that i borrow this thread.

I removed the auto heat to make a new connecting rod for the servo and noted some wires coming out of the auto heat unit that i don't know whats for. Does any one have any suggestions what the two brown wires are for?
The unit is from '79 930

[cmonref]

Second, when I went to locate the temperature sensor between my visors I found a hole in my headliner and two screws holding nothing but air.....so if you have an extra temp sensor laying around, I am in the market.

Yikes! The sensor part you need is NLA, and in years of watching, I have never seen anyone find one or seen one for sale in the classifieds.

In the hole in the headliner, is there a wire there with a connector on the end? That wire normally connects to the back of the sensor which is held in place by a rubber rectangle thingie held in place by the two screws. (See the pic below.) You can, if you are handy, install a thermistor of the right values and connect it to that wire, which will get your system functional. Without the right parts, you will have to figure out a way to mount your sensor.

The interior sensor is an NTC thermistor rated at 1.9kOhms at 20C/68F. Temp points above and below 20C/68F do not appear to matter much as long as the 20C/68F point is met.

Picture of the interior sensor:


Good luck.

[tirwin]

The poster asking about the sensor asked that about 6 years ago.

Jajohnsen, brown are typically ground wires in the European DIN wiring system. I'm not sure I have a wiring diagram that includes auto heat.

[cmonref]

tirwin: Oh, me! And I laugh when I see others respond to a really old thread!

jajohnsen: The only wires and are brown and loose like yours are with individual connections on MY autoheat go to the heating fan motor on the top left of the engine. They connect to separate yellow wires that poke out from under the carpet at the rear of the autoheat box. When the autoheat moves upwards off the OFF position, it turns the fan ON. All other wires in the autoheat have multi-wire connectors on their ends and have matching multi-wire connectors.

[tirwin]

It happens to all of us.

It has been several years since I fixed my autoheat. I had some notes I took while I was sorting it all out. Unfortunately I can't find them. The servo unit was good -- got lucky there.

[Jajohnsen]

Thanx for the replies.

Seems to me the two wires have never been used and if i understod tHe pet right there is no blowers in the engine compartment for the '79 930 so i guess they're suposed to be lose. In my case.

[JSV798]

I have a '78SC and have worked on this control unit at various times over the past 22 years. The part you show has the servo in it that operates the flapper boxes underneath to allow hot air to pass into the interior ( my car has levers as well by the handbrake so if the unit fails I can still open the flapper valves and get heat or I will be able to when I fit my newly purchased heat exchangers). It also switches on the fan in the engine compartment and that's what those two spare brown wires do. You should find two yellow wires under the carpet between the seat belt anchors.
The PO had messed around with the heating system; the ducting and fan in the engine compartment were missing as was the thermostat between the sun visors.
As someone remarked that thermostat is NLA but I did eventually get a used one from a breakers so that would be your best bet.
The best I have ever had my system working was that it would switch the fan on and open the flapper boxes; then the centre control unit stopped working so I just put a switch on the two yellow cables that emerge from under the carpet (and connect to those two brown wires) so that I could switch the fan on and used the hand lever to open the flapper boxes.
I bought a used control for about $30 and that worked for a while but that has now failed. Recently tried to switch parts between the two units with limited success.