E30 Zone

Hi,

First post here after getting my first E30.

It's a 1990 325i convertible, it's been sitting unused for a few years and I'm slowly getting through the list if things todo.

Here's how the car looked when I found it, and I had to try and save it:



Most have been simple enough, except the current job and that's no heat from the heater vents. It just blows cold air.

The car has the optional climate control which I understand wasn't a common option.

I've checked the heater valve and that works as expected and the heater matrix warms up as expected. The heater pipes from the engine are both warm so hot water is flowing through ok. I can also hear the heater valve open and close when I adjust the heater control.

However the motor that opens and closes the flap that send the air across the heater matrix doesn't open so the air never passes over the heater.

I bench tested the motor and it opens and closes fine with a 12v source.

I measure the voltage from the heater control and when the signal is sent to the motor to open the flap is a very low amp 12v. The signal to close it a strong ampage 12v and closes without problem.

It's a lot of wires in/out of the heater control (about 20 or so). So I assume a lot of different things are possibly measured. The climate control unit itself has a small fan to draw air in from the cabin to measure the temperature. Not sure if there's an external thermometer someplace. Although if it's the same one as the OBC it reads ok.

If anyone has a wire diagram for the climate control I'd really appreciate it or any tips on how to trouble shoot the climate control unit. Or in worst case even have advice on how convert to the normal unit.

Thanks
Alan

Here's the automatic heater control unit.



If anyone has a way to diagnose issues with it, or what sensors on the car are dependent on it I'd really appreciate the help.

Trouble shooting manuals here: http://www.armchair.mb.ca/~dave/BMW/e30/

Ben

Thanks Ben,

I saw those also, but for whatever reason (but I'll double check tonight) that the automatic heater control wasn't covered. I'm guessing since they're for North American cars and I don't think they had the automatic heater control option. But like I said I'll double check them to be sure.

Cheers
Alan

I've never found the circuitry in question amongst those manuals, or anywhere else, I'm afraid.
One worrying thing in the pic. is those two blue connectors - they don't look like anything I've ever seen used by BMW, suggesting that someone might have been there before, making mods.
If the fixings and lever on the heater box are present for the bowden cable to the flap, then it should be (only a guess) relatively simple to convert to 'manual' with an ordinary heater control knob.

Those two blue connectors are soon to be gone... Previous owners radio installation...

Btw Thanks Brian for the info... I'll try and see follow the loom a bit and see where it takes me.

I did find another temperature sensor on the drivers footwell close to the chime box. Cleaned the dust off that sensor but haven't done any measurements on it to see if it's a good connection of not.

Brianmoooore wrote:I've never found the circuitry in question amongst those manuals, or anywhere else, I'm afraid.
One worrying thing in the pic. is those two blue connectors - they don't look like anything I've ever seen used by BMW, suggesting that someone might have been there before, making mods.
If the fixings and lever on the heater box are present for the bowden cable to the flap, then it should be (only a guess) relatively simple to convert to 'manual' with an ordinary heater control knob.

Hi Brian,

I managed to test the system with another automatic heater controller unit and I got the same result unfortunately. I'm wondering if the temperature sensors are possibly reading incorrectly. Perhaps thinking the air in the car or outside is actually warmer than it is and possibly that's what's stopping the flap opening automatically... guessing a bit at the moment.


I think I'll test all the sensors and see what happens. I guess there's 4 at least... One in the Automatic heater control, Ambient Air sensor in the drivers footwell, Outside air temp in the wheel arch, and the evaporator temp sensor. I've cleaned up all the sensors except the Outside Air Temp so far...

To be continued....