The complete automotive resource for buyers, sellers, and owners like you.
Car, Truck and SUV Forums at Roadfly
+ Bentley Forums
+ BMW Forums
+ Cadillac Forums
+ Chevrolet Forums
+ Ferrari Forums
+ Jaguar Forums
+ Lamborghini Forums
+ Lotus Forums
+ Mercedes-Benz Forums
+ Maserati Forums
+ MINI Forums
+ Porsche Forums
+ General Discussion
+ Marketplace Forums
Sounds like thumbwheel microswitch (archive)
[ Follow Ups ] [ 7-series (E23) Message Board ] [ Msg. Board FAQ ]
Posted by stevecots on August 19, 2001 at 07:43:02:

In Reply to: Jens, others - help - bad HVAC solinoid? posted by Walter OH 84/733i 87/325i 83/635csi Euro on August 18, 2001 at 17:05:53:


My car is an '84 733i - 115k miles w 5 speed out of Texas

Pretty well maintianed and garaged most of its life.

I've been over most of the AC components (rebuilt the push buttons, put new brushes in the blower motor) and it normally works well. Jens told me that when it occasionally got confused and went click, click click for a while - it was the solinoids behind the ashtray.

It is now stuck in the default defrost mode, even though the other green leds will light DIMLY when selected.

Vacuum leak checked out no problem, passed leak down test and would hold 450 millibars at idle.

When I turn the fan thumb wheel up higher, the green led selected (like auto AC) gets dimmer. The blower only runs at part speed. The brain box doesn't shift when I change temperature selections or push different buttons.

If its a burned out solinoid, could this be causing all these problems? How do I get to them and whats the best way to test them? How do they actuate that wierd mechanical brain box by the driver's feet?

Any help or suggestions welcome.


Sounds to me like the thumbwheel microswitch because you are not getting full power to the pushbutton switch. The solenoid switch is vacuum only and either switches or doesn't, but would not effect the lights on the pushbutton switch. There are detailed instructions on how to take it apart and clean the contacts with 1000 grit sandpaper and then remount with tiny screws froom Radio
Shack back in this message board about two months ago. Sounds like you are very competant on repairing these things. If you need a thumbwheel switch I have extras, but you should be able to fix yours. steve847-251-1229 stevecot@aol.com

Follow Ups:


[ Follow Ups ] [ 7-series (E23) Message Board ] [ Msg. Board FAQ ]
Questions, comments, or problems, please visit the Roadfly help desk.
Roadfly.com Logo © 1997 - 2009 Jump Internet Inc. All rights reserved.