I have a duotherm double unit A/C setup on a 2003

In the main unit, remove the inner shroud and then pull down the control unit (two phillips screws). Remove the access cover on the control box to view the dip switches. The switches should be set to Zone 1 and Zone 2 to on and then the furnace to on (if so equipped). If the zones are not in the in position, then set them to the correct position and reset the thermostat again. If they are correct, try turning them off, resetting the thermostat and then turning them back on and resetting again. If this does not work, then you have a bad thermostat or control box.

Hope this helps,

Jeff