trader5904
Dec 11, 2006, 05:33 PM
Hope there is someone that can help me out my mother lives about an hour and a half from me and I was hooking up a thermostat for her heating and cooling unit her old unit was a rheem and the new one was a honeywell and the wiring digram was totally different is there anyone out there that can tell me how it should be wired for right now seams like the heat works well and the air works but the inside unit wants to keep running the only what to stop it is shut it all off can anyone please help me out here
labman
Dec 11, 2006, 07:38 PM
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, common, 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. Most thermostats and furnaces have the contacts labeled R, B or C, W, Y, and G for the corresponding wire colors. Many have RH and RC to allow separate transformers for heating and cooling. With just one red wire, jumper them. It may be wired to have the A/C 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. Digital or programmable thermostats may need the blue wire connected to them.