Cadillac Repair: 96 caddy fleetwood heater blows only cold air, cadillac fleetwood brougham, cadillac fleetwood

Question
Our 96 cadillac fleetwood brougham heater blows air--cold air--no matter what mode you choose from the climate control.  We live in alaska and this is inconvenient.  The temp up/down will scroll to 90 deg or down to 60 (and it blows even colder air out of every port when you select 60 degrees).  It doesn't matter if I choose defog or auto or econo or hi fan or low fan or any combination thereof.  I am a pretty fair mechanic-hen you grow up in alaska.  I've rebuilt my share of motors and replaced every part you can imagine.  On a previous answer you mentioned a PROGRAMMER near the glove box.  Okay, That may be this car's problem too (we rarely used the heater because we only drove this car in the summer and kept it in the garage year-round) SO...how do I test and/or fix or replace the A/C programmer?  By the way, we one had a '84 Caddy we bought in florida and the gate valve that regulates the antifreeze flow to the heater core was completely corroded shut due to non use of the heater.  I thought that my have been the problem with this car but I couldn't find anything similar under the hood.  Thank you for your time.  

Answer
The 96 uses a completly different system then the one you read.

See if you have any codes in the HVAC system via:

1. Turn ignition switch to RUN.

2. Press the OFF and TEMP ^ buttons on the Heat/Ac control unit until -00 is displayed.

3. push the out-temp while -00 is being displayed and then push the fan insignia ^ until you see -02.

4. Are there any other numbers displayed ?. If yes, I need to know what they are. Push the outside temp button and see if there now are any numbers displayed.

5. push AUTO to exit diagnostics.