84 5K Avant climate out of control

[J4KQ4me@aol.com]

Hello, again-

  Any insight into why my 84 5K avant's climate control blower only operates
on defrost? For other reasons, (Or should I say the usual reasons) I've
replaced the blower motor, the head unit and the programmer. The blower will
always come on in Defrost, but will only occasionally operate in any other
mode.  Is there a control unit for the blower? Is it the one on the plenum
under the cowl cover? I can't find enough info on the system... Thanks again
Harrison! It's bad enough the rack leaks like a saginaw product. 
   Second point- On my friend's 86 5KCS the radiator fan is completely inop.
I've checked relay function, and it is functioning fine, ie when thermo switch
is juimped out, relay closes. When I apply direct B+ to the terminals on the
fan, it runs. Is there a resistance pack for the fan motor, like the one that
is blue by the left front fender? Or is that for the clim. control?
  Thanks again!

   Jon

87 GTcpe 2.3
85  4kSQ
84   5K Avant