Cadillac Repair: heat not blowning out my vents, cadillac fleetwood brougham, 1996 cadillac fleetwood

Question
I have a 1996 cadillac fleetwood brougham and the heats blows out the top vent on the dash but won't blow out the other vent's and the air is cold when I have it set at 90 high. I replace the  thermostat and then the radiator and still having that problem.

Answer
You most likely have a fault with the AC/HEATER PROGRAMMER.

If you remove the glove box liner, Look for a black box that has a threaded metal rod on the top and a multi colored vacuum terminal near the bottom.

While watching this threaded metal rod, Put the system on FULL HEAT an this ord should come towards you about 2 inches and stop. Now put the system on full AC and this same rod should move away from you about 3 inches, Does it ?.