<E28> Heater works now! solution:

[bolhuijo@xxxxxxxxxxxx]

 I have a perfectly working heater again!  Of all the things you can
fix, this is one of the most satisfying.  Here's the deal:
 1> Several people (and the FAQ) suggested that the heater control
valve had failed.  I took it apart, inspected it, bench tested the
solenoid, and came up with a perfectly functional valve.  Even though
it ain't broken today, I know it probably will, so I'm prepared for
that inevitability.
 2> The cabin temp sensor can also fail.  I removed mine, cleaned it,
measured it, and found it to be in spec, thanks to the figures beamed
to me by Ray Kaupp.  I also discoverd the vacuum hose was no longer
pulling any air across it.  The hose was disconnected from the
manifold.  A hard plastic vacuum hose from the sensor proceeds through
the firewall, and jams into a short piece of regular vacuum hose
attached to the very bottom of the intake manifold.
  Despite the disconnection, the car's idle was not affected because
a> there is a tiny flow restrictor inside the rubber connector hose (I
can't belive I found that), and b> that flow restrictor was plugged
solid with oily dirt.  A new bit of hose, and a cleaned out flow
restrictor, and all was well again with the cabin sensor assembly.
 3> The sensor inside the heater box is another suspect.  Huge thanks
to Larry Franks, who pointed out that it's not as bad as you think to
find it.  Removal of the drivers side underdash panel is all that is
required.  The sensor is a white nylon probe stuck into the black
heater box near the drivers foot vent, close to a relay assembly.
Testing of this probe showed an open circuit.  I pried the 2 halves
apart, re-soldered some very small wire, and I was good to go.
 A short test drive was all I needed to tell me that I didn't have to
pull the console apart to test the control / rheostat assembly.
Instead of almost binary HOT or COLD action, the heat was moderated.
WooHoo!
 And now, to end this already long email, is a list of people who
don't suck!  (that is, in addition to the many others who I will not
name for brevity's sake)
 In no order: Paul McCormick, Bob DiLeonardi, Ray Kaupp, Michel
Potheau, Nikos Mouat, Curtis Kiser, Erick Baumeister, Delford Chaffin,
Larry Franks, John G. Burns.  Apologies if I missed anyone.
 Thank you all!

 --
  John Bolhuis  | Since announcing concubine auditions in April,
 bolhuijo       | I have received not a single reply. Foolish females!
  @domain.elided | Do you not realize that I am one of the richest and
                | most powerful men in the Republic?  -T. Herman Zweibel

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