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<E30> Intermittant Fan Speed Problem



In BMW Digest v09.n172 Scott Miller reported an intermittent heater
resistor pack failure:

> the heater fan only worked on the "high" setting

then later:

> On the way home I turned on the fan and discovered that all 4 speeds
> work now.

And in v09.n173 Chris Pawlowicz <chrisp@domain.elided> and Russ 
Poffenberger <poffen@domain.elided> described a repair by 
resoldering the pack's soldered connections.

The E30 fan speed resistor pack I've seen was constructed of a plastic
body to which are *riveted* the terminals, resistors, and a few
conductor strips.  I hypothesize that the rivets eventually loosen 
from a combination of vibration and heat-softened plastic.  Once a 
connection is slightly loose, the heat produced by the additional 
resistance would make it looser.  It's easy to imagine that random 
vibration and heat cycling could make a marginal connection come and go.

If repairing a riveted pack by soldering the connections, be sure to
solder each rivet end that makes a connection.

Curt Ingraham
'72 2002tii
Oakland, California

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