[RedBeard12]

I have an american standard ASYSTAT655A thermostat I want to replace with a 3M-30. I currently have the following wires on the american standard hooked up- Red-R, Blue-B, Yellow-Y, Green-G, Brown-X2, Orange-O, and White-W and linked to U. there is also a black wire that is not used. From the info I am reading this is a heat pump unit if that helps at all. I just want to know the wires I need to hook up for the new one. My confusion is with the X2 brown wire and the black wire. Along with the white being jumped to U.

[Stevoway]

Check you're connection at the Units end to locate all the wires going to each connection, then figure where or what they are for...