No vent heat or floor heat only defrost heat

I have a 1991 ford tempo gl with a four cylinder engine, 172000 miles on it. Just recently the air for the heater control stop working for my vent and my floor all I get is defrost only I went to the junk yard and picked up a heater control switch thinking the old one went bad but that was not the problem. I looked at all the vacume hoses under the dash and they all seem to b e in place, I can manually push in the plunger under the dash and get floor heat and the plunger for the vent and they both work fine manually but since I cannot drive with my feet up in the air and my head under the dash I would think it is one or both plungers that are bad, what do you think

Minguelli