Heater control advice.

[ss2115]

How seperate should the left and right heater controls be on my 1993 E34 - standard round dials and fan dial?

The reason to ask is that my drivers side heater dial turns with slight resistance as if its doing something, but the passenger side turns very freely.
Additionally, it seems that the drivers side dial is doing all the work - ie: it seems to make change the hot and cold air on the passenger side exactly the same as the drivers side.

Its a bit hard to tell, but turning either side hot and the other side cold doesn't seem to make much difference - whatever the drivers side is set at is what they both end up being.

Air to the feet on either side is very weak and not impressive on either side.
Air to the centre vents and windscreen is good and strong.

Any advice?
Any common problems that this forum has discussed previously?
Any more advanced testing I could do to see if there is a problem or not?

[shogun]

in emeregncy mode the driver side thumb wheel overrides the passenger side, so if you turn driver side to max over the click, the passenger side will follow and there is no adjustment possible on passenger side, same with coldest adjustment. Maybe one side is defective.
You have to study German language ;-)
>50 pages to read under
Klimaautomatik IHKA (German language PDF)
http://www.e38.org/e32/

but there you can see all the measuring data and how to test, so even if you cannot understand German it will help you a lot. That is one of the best tech training manuals I know for this. Download it.

[ss2115]

in emeregncy mode the driver side thumb wheel overrides the passenger side, so if you turn driver side to max over the click, the passenger side will follow and there is no adjustment possible on passenger side, same with coldest adjustment. Maybe one side is defective.
You have to study German language ;-)
>50 pages to read under
Klimaautomatik IHKA (German language PDF)
http://www.e38.org/e32/

but there you can see all the measuring data and how to test, so even if you cannot understand German it will help you a lot. That is one of the best tech training manuals I know for this. Download it.

Mine is not the thumb wheel of the automatic climate control system.
Mine is the standard heater controls with vertical dials.

[shogun]

sorry, this one I have no experience, even never touched one.
They are very rare on E32, maybe only supplied on some German E32.
But the E34 owners for sure can help.

[sal_park]

Mine is not the thumb wheel of the automatic climate control system.
Mine is the standard heater controls with vertical dials.

If by vertical dials you mean this:


then I can tell you that as per the climate control version shogun mentioned, the drivers side control has a detente at maximum and minimum which will cause the heater to ignore the passenger heater control and deliver maximum heating or cooling. As to the resistance of these they can be next to nothing and still working correctly since they are variable resistors and don't control the flow of the hot water directly. FYI my passanger heater control is much much lighter to turn than my drivers heater control, but both work fine.

hth

sal

[ss2115]

If by vertical dials you mean this:


then I can tell you that as per the climate control version shogun mentioned, the drivers side control has a detente at maximum and minimum which will cause the heater to ignore the passenger heater control and deliver maximum heating or cooling. As to the resistance of these they can be next to nothing and still working correctly since they are variable resistors and don't control the flow of the hot water directly. FYI my passanger heater control is much much lighter to turn than my drivers heater control, but both work fine.

hth

sal

Yep - those are the ones I mean.
I was surprised when you said they were electrical. I assumed they were vacuum controls to operate vacuum flaps and valves. So are the flap controls etc steppermotors?

I did find the detents at each end of the drivers side control, but I'm not using these as I find the comfortable temperature is at the halfway setting of around 22 degrees. I usually have the fan at #1, as I find #2 is a fraction too noisy, and moving back to the variable section doesn't blow enough.

Is there any procedure or sequence documented anywhere for testing the electrical side to see if everything is working properly?
Is it possible to operate the controls and see anything moving under the dash to confirm it is working properly.

I just don't think its working as well as it should.
The hot isn't hot enough when I do want maximum heat occasionally, there's bugger-all air at either the drivers or passenger footwells, and there's no effect of the passenger side heater control.

[tim eh?]

I can only suggest a couple of things that probably aren't the problem but worth checking.

first you can easily pull the temperature dials off their knobs and see maybe if the passenger one is busted and not turning the pot properly.

second... about the airflow undernaeth... the plastic conduits underneath the dash can be a pain to reinstall properly and if they are not aligned you will get lousy airflow under the dash. (ask me how I know)

hope it helps a little... I can't think of anything else to suggest.

[sal_park]

I'll suggest looking at the heater valve first