On my 93, the heat comes out through the dash vents only. You can push the defroster button but that doesn't change the air flow. Nothing comes out of the floor vents either. Checked the sticky but couldn't find anything helpful. Checked the service manual, it says that if the actuator fails, it will fail in the defrost position. Just not sure where to go from here.
Thanks,
Bill

 

Could be a combination of failures, linkage gummed up, etc.

Good place to start would be to be sure you have vacuum to the control set.

 

Do I need to pull the controls out of the dash to check that?
Bill

 

Check for vacuum on the line that goes to the check valve/filter. That is your supply. It's under the dash, the lines come through the firewall near the heater hoses

 

Looks like an electrical plug...kinda clear w/ red,green,black,blue etc. Unplugs real easy.

 

OK, thanks. I'll check that.
Bill

 

Another possibility is that the moveable blend and defrost doors inside the HVAC box have seized up, I've seen it happen.