Automatic heater control
 

Hi folks I want to keep car as it was so not looking to create a manual heater setup. My automatic unit dial just spins round. Do I have any chance of fixing or is it only fixable by replacing the whole unit?

Any experts / DIYers here?

Thanks a lot

Do the blowers turn on at all or does the dial just spin around freely without "doing anything"?

I'd try checking out the inside of the control housing, the problem might just be with the dial and not the inner workings. A little more description would be helpful though.

Thanks - the dial just spins and does nothing. I've just set the heater fans at the rear to be half open. If I take the unit off is there any clue as to what to check to decide if the damage is terminal?

Heat.
 

pm me.

Gerry

Locale? Somebody nearby might be able to help.

I think I have one if you decide to replace it. But let it be a last resort.
- Matt

What year P Car are we talking about? Your garage states 2013.

I'll venture into this. If it's a autoheat car have you removed the knob? and is the knobs plastic tab still in it? Or have your checked the reostat? is that what's turning?
I'd think one of the Pelican bro's would be able to help. A few have rebuilt a typical auto heat controller.

Sorry - it's 1983 SC. I haven't removed the knob. When I look down it has the red background with numbers on it but when you turn the dial it feels sort of loose.

Thanks

Pull the knob off to start. It may be that the plastic "rib" that aligns it to the shaft of the autoheat servo is broken. You should be able to turn the servo portion from 0 (blue) to 9 (red) with it stopping at both 0 and 9. If you turn it counterclockwise it should pull the heater boxes wide open and if turned clockwise to 9 it should pull them closed. As well, when operating the servo you should be able to hear just slightly the servo activating the arm that pulls the cables.
You could have :
1 broken knob (no biggy get a new one)
2 broken servo , yet to be determined but can be rebuilt
3 issues with mechanical movement of the cables
4 stuck heater boxes.
Start with the knob it'self and move deeper. Check previous posts regarding autoheat for reference and in my opinion the auto heat in an 83 will either not work, work all summer when you don't want it to, or melt the hair off your legs.... but it does actually heat my 83 better and quicker than my new Toyota

Pull the knob off to start. It may be that the plastic "rib" that aligns it to the shaft of the autoheat servo is broken. You should be able to turn the servo portion from 0 (blue) to 9 (red) with it stopping at both 0 and 9. If you turn it counterclockwise it should pull the heater boxes wide open and if turned clockwise to 9 it should pull them closed. As well, when operating the servo you should be able to hear just slightly the servo activating the arm that pulls the cables.
You could have :
1 broken knob (no biggy get a new one)
2 broken servo , yet to be determined but can be rebuilt
3 issues with mechanical movement of the cables
4 stuck heater boxes.
Start with the knob it'self and move deeper. Check previous posts regarding autoheat for reference and in my opinion the auto heat in an 83 will either not work, work all summer when you don't want it to, or melt the hair off your legs.... but it does actually heat my 83 better and quicker than my new Toyota

I had trouble with mine.My problem turned out to be the linkage came off the switch.I recall you can take a few screws off the side of the switch to gain entrance to the linkage.Ah,it`s worth a try.

I had a similar problem and this is what I found when i pulled things apart, it might be of some help. go to page 4
http://forums.pelicanparts.com/porsche-911-technical-forum/758709-old-911-new-owner.html

An 83 with autoheat will not have the electrical contact connected to the knob as noted in Caledonian's post.
It's just a knob with a aligning part that goes onto the reostat shaft.

Thanks to you all for these posts I really appreciate it.

I have an '83 SC with auto-heat too. About a year ago I refreshed the interior. Before that the heat was really only on or off. After driving for a while my toes would be baked so I would alternate on/off to regulate the temp.

There are a few things that can can act up. Your dial is spinning so you need to look there first. Take the seats out to access the auto-heat console. There are 4 Allen head screws that bolt the console to the center tunnel. There are also a couple of access panels on each side so you can see the controller board and the servo motor. The dial is part of the plastic housing. Be careful in taking it apart and make sure you take pictures of how the wiring connects together. I don't recall if it's possible to just replace the dial if it's cracked. You might have to find a used housing with a working dial.

I'd try to make sure the auto-heat works properly so you know if you just need the dial/housing or if the problem is deeper than that. When I started disassembling stuff to take the headliner out I found the thermistor in the rubber nipple in the ceiling had come loose. There is a procedure for checking if the thermistor is still good. I think it's measuring the resistance. That seemed to be the thing that fixed my problem.

The other things is making sure the servo motor works, the cables to the flappers are good, the flappers open/close properly and that the footwell blowers work.

You should be able to turn the rheostat shaft with a pair of pliers to check if the control board works and the servo motors turn. I'm going from memory here so if you run into something that doesn't make sense let me know and I'll try to help.

Thank you very much - I'm very early in process and have looked through access point but because when I turn dial nothing happens I wasn't sure what to do.

I have an issue now certainly where the heater boxes need lubricated or refurbed but I can do that as part of the fix.

I'm unclear whether the motor works so it sounds like I need to assess that. How do I turn the rheostat shaft ? Is it under the broken dial?

At least then ill know if it's a dial issue or control board issue.

Thanks again

I think if you take the plastic housing off you will see if the dial is turning the rheostat below. It sounds like the plastic dial is broken. When the rheostat turns normally it clicks at each position. The shaft is notched so that the dial fits on it one way like the tuner knob on a radio. If the dial is broken you should be able to see if everything else works by turning the shaft with a pair of pliers.

At each position the servo will activate and pull the levers for the flappers more open or closed. It's kinda like the dial on an old rotary phone... when you go from the off position to 9 it takes the longest because the servo has to move the lever arm the farthest. There is a delay of a second or two for each notch so you will hear and see the servos turn with the housing off if they are working. That assumes that the cables to the flappers are also working properly.

Hopefully that makes sense...