______________________________________________________________________ I recenly purchased an older house that had been sitting empty a few years. The wiring from my thermostst to my furnace was all disconnected. I was able to get my furnace working, but now I’d like to get the AC working. There is power going to the external AC unit outside the house, and I have a low voltage (I’m assuming) wire coming from the AC unit to the furnace, but the (2) wires aren’t connected to anything. Should I just be able to touch these two wires together, simulating a thermostat and the AC should kick on? Other then that, I have no idea where on my furnace these to wires should go. The furnace is an older model Johnson HAS105A and the AC unit outside is a Janitrol CK24-1b. I’m not even 100% sure the thermostst is wired correctly, but when I turn it to AC and the temp down, the fan will come on. Is there anywhere I can look to see what the correct wireing diagram should be, or a way to test the AC? Thanks, Bill Replies: Xenos “Re(1):Can I bypass thermostat and check AC?” , posted Sun 28 May 12:01 ______________________________________________________________________ One wire connects to C on the furnace and the other to Y connected to both the thermostat and furnace. Y is powered to start the unit and C is common. Xenos. The best way to escape a problem is to solve it. FlameOut “Re(2):Can I bypass thermostat and check AC?” , posted Sun 28 May 13:14: ______________________________________________________________________ There is an Orange wire coming from my thermostat, right now it doesn’t go anywhere. I think it might go to Y or C? When I put the Orange wire to Y, the Compressor hums, but doesn’t seem to do anything else. Also, the fan above the compressor doesn’t come on. Not sure if that is supposed to run the entire time the compressor runs or just comes on to help cool it [this message was edited by FlameOut on Sun 28 May 17:37] chris442 “Re(3):Can I bypass thermostat and check AC?” , posted Thu 1 Jun 21:02 ______________________________________________________________________ Xenos is right. You should be able to ignore the orange wire IF you have a yellow wire from the stat hooked to Y in the furnace. Double up one of the two wires from outside under the Y terminal screw and put the other one on the C terminal. I’ll bet the outside unit has problems, and that was why it was unhooked in the first place.