5K Heat Question

[Steve Sherman <spsherm@ibm.net>]

I'm having an "interesting" problem with the heat on my 86 5kCSTQW...
One that I have not seen before on this list. It goes like this...

The heat seems to work normally at first.  It comes out the right ducts,
after the engine warms up a bit.  Blows hot air, hard at first then the
fan slows down as the interior warms up getting close to the set temp.

The problem is that by the time that the interior has warmed, the slow
flow of air has changed temp, so that it is blowing out relatively cold
air.  That air is hotter than outside air, but  much colder than you
want on a cold day or nite.

If you keep moving the temp up you can get around this for a while, but
my other 5K doesn't have this problem, it blows warm air when up to temp
without playing games with the temp setting...

I am puzzled as to what might cause this.  I tried a different climate
control, but had the same symptoms.  The heater valve is new (~ 6 mos
old), and the system can produce lots of hot air when it wants to?

Any suggestions out there?


Steve