Re: to Charles V. Stancampiano HVAC question (archive)

Hi,
I appreciate your efforts. Send email to cvs "at" ieee.org .
When I fixed mine I didn't have a circuit diagram. I just found that the output transistors (or at least one of them) were shorted (emitter to collector) and replaced it. There are two final stages in the blower assembly. For testing purposes, the motor will work with one of them unplugged so you can narrow down which one is bad. Each final stage has two large transistors in parallel. If either one is shorted, the motor will run at full speed any time it is on.
Remove both transistors and solder/screw in new ones. See if you can get one final stage to run. Then worry about the other one.
Pinout for T03 style power transistor:
View from bottom (pin side).
_
/ O \
/ o o \
( B E )
\ /
\ O / C
_

B = Base, E = Emitter, C = Collector.
The metal case is the Collector.
Just put them in the same way they came out. The pinout is not symmetric so you can't put it in wrong. Make sure any insulating material under the transistor body is put back under the new part. If you need more help, email me.
Charlie

I tried to send you an email question about the Blower motor electronics. Got an error on delivery problem. I need more info on the speed control module inside the blower motor. I appreciate the info you provided in a reply post but I still don't have enough info to fix the problem. If you have any diagrams of the system I sure would appreciate a copy (if anyone else has a clue please post me).
This model BMW has poor cabin ventilation without a good working blower system so the problem is one that can't be ignored.
Thanks

Follow Ups:

Thanks Charlie !!! Russ 21:24 9/02/2001 (0)

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