One outside unit &two inside units, summer no issue ,winter impossible 
to control the temperature in my bedroom problem heat transferring from lower unit to bedroom unit if lower unit is set to 75F ,upstairs set to 65f the room gets to hot for sleeping even in fan mode heat is still blowing out, solution  close the upstairs unit in the winter bedroom door always closed.Sharp tels me that this normal with all the makes dual zone systems. Any help would be appreciated 
Regards