540i heater control upgrade?

[wmann]

I saw a 1993 m5 a while ago that appeared to have a heater control system that was more like the upgraded controls in a newer (e39) 540i. By that I mean that you set a temp and it controls the adjustments vs the 3 knob system that was and is used on some lower level models today. Was this a 740/750 style control that can be used in the e34 5 series? If so has anyone done it? Thanks for the info.....Bill

[Paul in NZ]

i have that system and i think i would prefer the manual system
http://www.bimmer.info/bmw/kiwi535/Picture%202a.jpg
one reason is that the windscreen defrost function is a push button which puts the fan on full(and its NOISY) and directs all air to the screen.The other option is to manually close the fascia and dash top vents via the thumbwheels and crank the fan up or run the air cond.....The auto control is pretty average too,unless you can get for free I wouldnt bother.

[wmann]

really? it doesnt work well? Will it shut off or start up the fan as needed? do you know if its a bolt in replavement to the manual or does there need to be other mods? Thanks! Bill

[winfred]

it's not a mod we just didn't get the full auto system on anything but the m5, it's more like the system in a e32 and i don't like it as much as the regular system, i hate systems that don't allow you to manually adjust the airflow to whatever vent i want when i want it, i gotta sat the e34 has one of my favorite hvac systems for controls, the e30 would be perfect imho if it had the thumb wheel to control the mixing flap like the e34

[shogun]

only a few of the early E32 have the other control and also some European E32 w/o aircon (yes, that was an option in some countries) . It might be difficult to understand at a first glance, but for me it works fine now.
I seldom use the auto button in the middle, prefer the manual adjustment with the thumbwheels on center and outer vents at the dash.
Also when set on auto, not much air will come out of the center vents, as thru these always mixed air is coming = cold air (now in winter) from outside and warm air from the heater system. The colder it is outside, the less air is coming out of the center vents when temp wheel is set to 28 degree C for example.
Johan has made a nice info on this system (http://shrubbery.student.utwente.nl/johan/ihka/ihka.html)