Cadillac Repair: 1996 cadillac fleetwood, 1996 cadillac fleetwood, cadillac fleetwood

Question
Hi Tom,

This car heater is only blowing to the defroster and its cool.  It doesn't go to the vent or floor.  The lower hose going to the heater core is hot, the upper hose is luke warm.  One year ago they said the heater core was clogged and they flushed it out.  They also replaced the programer.  The vent door is moving and adjusted properly.  I made HVAC run through its self diagnostic run. It didn't have any codes.  Can you please help?  

Answer
The most likely cause is a loss of vacuum from the engine compartment to the black plastic vacuum line at the programmer.

See if you can locate the vacuum line, Most likely a small black plastic line that goes thru the firewall and into the passengers compartment for being loose and or busted and repair it.