New twist on traditional HVAC Problems (archive)

I know that the most common cause for a lack of all but high speed blower operation is a failure of the final stage amplifiers in the blower motor housing, but I my problem has a different twist. At the same time that the variable speed stopped working, the defrost function stopped working as well. From examining the wiring diagrams, it appears that the high speed operation of the fan from the thumbweel control is done through the blower relay via the in-dash control board, but the high-speed operation for the defrost mode is done through the high-speed relay via the A/C control unit in the driver's footwell area. I know that the A/C control unit also controls the final stages for variable operation. Is this true?? And if so, do you think that the A/C control unit is the likely suspect??
Thanks for any input,

Patrick
'84 733i

P.S. In the event that it is the final stages that have blown, does anyone know where to find a list of components needed to rebuild them?? I know I've seen directions before, but I haven't been able to find them in the archives.

Follow Ups:

Re: New twist on traditional HVAC Problems Tom M. 23:36 2/01/2001 (0)
High Speed Voltage Grant 14:59 2/01/2001 (0)

[ Follow Ups ] [ 7-series (E23) Message Board ] [ Msg. Board FAQ ]

Questions, comments, or problems, please visit the Roadfly help desk.