Hello, I own 2 firebirds, an 84 trans am, and a 87 formula 350. on both cars no matter what selection i put floor/air/max it only comes out of the top of the dash(defrost). Both cars i have the original air conditioning compressors,condensors,and accumulators removed. I was hoping someone else had encountered this same problem. found a few people with the same question on the archives but no awnsers. mabee something to do with the a/c being unhooked. i know the controls work off a vacume system. all controls used to work on the formula untill i rebuilt the engine and removed the a/c. any experiences/help would be greatly appreciated!
SHIFFS

 

you have a vacumn leak in the heater control system, make sure the black plastic vac line under the hood is attached to the intake

 

You might do a search. The problem is common to thirdgen cars.

JamesC