Xmas draws night and a young man's fancy turns to...

["Tom Borden" <te.borden@xxxxxxxxxxx>]

Heat, of the automotive interior kind.  Issue is that heater works up to
about 55 mph, but thereafter, heater/vents blow cold.
 
I did pull out my heater control (vertical module with two stems to
hoses, located in engine compartment, driver's side) and that looks
rough (washer around body has gone wavy/bent, rubber washers down below
appear gouged).  At $80-100 for the part, I could replace that, but I
also remember reading that heat/no heat at different speeds was sign
that some filter might be plugged. 
 
Does anybody know where that filter is located on a 1988 528e, what it
looks like, how accessible it is, and whether any special tools are
needed?
 
Thanks all, and happy warm motoring this winter.
 
Tom Borden

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