No heat on floor or defrost can move selecter but only hot air at dash difusers ?

In the attached drawing, Part 32 moves Part 26 to direct the air flow to the desired locations. It uses vacuum to operate. The actuator may be bad or the vacuum hose my have come loose when the heater core was changed. With the car running but the blower off stick your head up under the dash on the passenger side and see if you hear a hissing sound. If so it's probably just a vacuum hose come off.
AIR CONDITIONING AND HEATER UNIT BODY Fits DYNASTY LASER LEBARON NEW...

sounds like vaccuum line problem or vaccuum assist

I assume your heater setting is electric control, if so either your defrost and floor heat switch failed or wire problem. For the air not hot, check the heat control valve on the top of the hose it should be in front of the firewall. I don't know your car is using mechanic valve or electric control valve. Anyway check there first. Good luck.

The most common problem is a stuck or faulty blend door under the dash.

defrost is the defalt mode look for a damaged vacuum line going ti the control head

Could be the control switch itself. Or possibly the actuator that moves the door from defrost to heater. With the heater on, try switching from defrost to heat and try to hear if you can hear anything in the dash operating.

One of your deflector door servos or the door itself, is hanging up. To determine this more clearly, run your vehicle for about two minutes and shut down the engine. Move your function selector knob from defrost to floor to panel and listen carefully for a sweeeping sound. if you do not hear this sound you've got to check under the dash for a loose vacuum line or under the hood for a loose or broken line to the vacuum accumulator. The vacuum accumulator is a large black ball on the firewall with only two lines connected to it. One line is about3/32nds of an inch and the other will be about one quarter inch. Check these lines well, for they control ALL the functions within yout climate control. Best of luck my friend, Dana

the blendor actuators strip out the gear inside the actuator cases on these all the time. replace the actuator.

common problem, check under dash by the gas pedal if control arms are muving went selecting from ac to heat cuz this it is the control for the vents to go from ac to heat and to defrost.

The climate control was poorly designed on these cars.

There is only heat on the floor and defrost settings, due to the layout of the ductwork.