I have a coleman presidential II unit. My heater works fine but my A/C will not shut off. We have to work it manually. It doesn't matter where I set the thermostat it just keeps running. :confused:

First try disconnecting the thermostat wires from the thremostat. If ac still runs, disconnect thermostat wires from furnace control board. If ac still runs, You most likely have a stuck contactor on the outside unit. Let is know how the first two test go. ( kill power to furnace before disconnecting wires)