Cadillac Repair: 1991 cadillac deville hvac, floor vents, cadillac deville

Question
the heater doesn't blow hot air out of lower heater vent even when set on 90 deg. the heater control door is moving engine is hot  it's like the air is not going through the heater cor  but the air comes out the bottom vent

Answer
Put the system on FULL 90 degree heat at full blower speed.

Wait 3 minutes and then disconnect the threaded metal rod from the plastic clip on top of the PROGRAMMER and pull the threaded rod towards you as far as you can and see if you get heat from the floor vents. Snap the rod back into the plastic clip while still holding it all the way towards you.

If your NOT getting any HEAT from the floor vents, You most likely have a plugged heater core.