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JJ I can send you information, see my comments (archive)
[ Follow Ups ] [ 7-series (E23) Message Board ] [ Msg. Board FAQ ]
Posted by Grant on September 15, 2000 at 19:00:48:

In Reply to: Re: E-23s only mount in the blower section posted by JJ on September 15, 2000 at 12:08:09:


I'm in the process of replacing the blower on my 733(thanks to Grant for help in diagnosing the problem. He nailed it with just my half-ass description of the problem). The Heating/AC system in these cars seems very comlicated with the switches, relays, solenoids, etc. I don't understand what the stage system is or does. Would you give me brief explanation. Thanks


You'll need both sides, as both transistor packs need to be replaced. The later E-32s had the infamous "sword" final stage , mounted in the front section of the heaterbox housing, to get blower air across them for cooling.
The mounting of the parts in the air stream of the blowers is important, you blow the final stage out on the latest E-38s if you run the blower with the hood up. There are 2 duct opening arms that are attached to the lower side of the hood. With the hood open, the intake ducts to the heaterbox are closed, and the result can be a damaged final stage pack and the loss of the blower too. Silly design, meant well but too easy to damage in a shop or home enviroment if you forget.


JJ, click on my name and then send me a mailing address and I will send you the chapter on the HVAC from the BMW manual. After reading that you will be an expert on the system. No charge. If you want to fix the amps yourself let me know and I will send you the schmatic for the amps so you can trouble shoot the board. Or as Callan stated just change the power transitor on each board as they are the most likely suspect. I think the last time I did a couple of boards the transistors cost about $5.00 each. Takes about 30 minutes to change them.


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