HVAC unit problem:

[Preston Brown <pbrown@econ.yale.edu>]

Hi, I'm still trying to iron out some of the little "features" that came 
with my '86 5KCST.  Here's the next one (and perhaps the most annoying):

The blower in the cabin is always on.  If I press "off" on the climate 
control center, it seems to adjust it so that more air is blowing at the 
windshield (defroster) but the motor doesn't turn off.  Additionally, the 
"high" and "lo" settings have NO effect.  I think that the blower is 
probably on high, because it is quite noisy.  Adjusting the temp. 
settings seems to work, as I CAN stay warm or cool.  But the damn fan 
won't shut off.

Unplugging the HVAC unit from the wiring harness didn't solve the 
problem.  I thought that unplugging it might show if the unit was 
defective or if it was in fact something else.  No luck -- the fan was 
still on. I plugged it back in.

So, does anyone know what the source of my trouble might be?  Where can I 
start looking/probing?  What do you think is broken, and how can I fix 
it?  Thanks for any suggestions.

---
 -Preston Brown
  preston.brown@yale.edu