I had some work done by a repairman last fall because my pilot would not light. He said it was a wire that came loose and fixed it. Now, my compressor won't come on. Blower comes on fine. Based on some other concerns with this repairman and the previous problem, I suspect wiring. Plus, there is a green wire hanging loose that was obviously crimped onto a connection previously.

Pics of my transformer wiring:
http://www.hqgear.com/images/115_1508.jpg

Pics of my thermostat wiring:
http://www.hqgear.com/images/115_1510.jpg

Any advise would be GREATLY appreciated.

Mike

Usually there is a 24 volt AC transformer in the furnace with the secondary winding connected to a red wire running to the thermostat and a blue wire to the gas valve, A/C relay, and fan relay. From the thermostat there will be white wire to the gas valve, yellow to the A/C, and green to the fan. The thermostat is wired to switch the power from the red to the white, yellow, and green as needed with the blue completing the circuit. It may be wired to have the control wires return to the furnace and its controls and then a second wire goes to the A/C unit. Internal wiring may replace the green wire if the thermostat does not give you the option of fan only or continuous fan.

Your thermostat follows this convention. It has the Elbe wire it should have for all but simple, dumb switching only. The transformer is a little different. I think the other secondary contact which usually has the blue wire connected to it is the one on the upper right with the one white and black wires connected to it. You need a pair of wires going to the coil of the compressor relay. Often they are yellow and blue. One needs to connect to the Y terminal at the thermostat. Often a yellow wire runs back from it to a terminal block at the furnace, maybe the Y terminal on the transformer. If that loose green wire runs to the compressor along with another wire, likely just connect it to the Y terminal on the transformer.