It depends on what thermostat you already have. If its an analog thermostat you can't add another unit to it. If its digital with two zones you can. If its digital with one zone you can't add to it either. The simplest and cheapest thing to do would be to add an A/C to the bedroom with an air box with a built in thermostat. Then its just hooking up the 110V wiring. If it is hooked up to the ducting, which I doubt, you'll have to tape up those outlet holes to use an A/C like this. You could add one to the bedroom with a thermostat on the wall if it is indeed ducted. It will have a digital thermostat which is an extra $100 and you'll have to figure out how to run the wire for the thermostat in the wall. The wire for these thermostats is basically a telephone wire with plugs on each end. It just plugs into the compressor and the thermostat. They don't even make a replacement A/C unit that works with the old analog thermostat anymore and if your replace one like that you'll have to put in a digital thermostat anyway. If you do that you can use a two zone thermostat and run both A/C units off of it. The thermostat will have to be in a central location where you can get the wires from both A/C's to it. I replaced my front A/C, which was ducted, with the unit with an air box. It had the old analog thermostat and I didn't want to fool with the installing a new digital one. It was a straight forward easy installation. the hardest part was getting the unit up on the roof.
