Cadillac: 1992 Cadillic Heater Problem, vacuum lines, plastic vacuum

Question
The car is a 1992 Cadillac Deville, 4.9L engine 210,000 miles.  With the electronic temp setting at 90 degrees, warm air (mild) only comes out of the defroster vent on passenger side only the other vents there is nothing or very little cold air its hard to detect.  A/C works fine.  Any help will be greatly appreciated.

Answer
Up under the dash on the passengers side you will see a group of different colored plastic vacuum lines that are attached to the PROGRAMMER. Right in the center of these hoses is a 7mm nut, Remove the nut and pull the vacuum lines off and see if you have vacuum at the BLACK hose.