How Do I Wire an AC Thermostat?
You just bought a new thermostat but which wire goes where?

When removing the original thermostat either take a picture of how it currently wired or mark the wiring and terminal designation for future reference if needed. Also below is a basic reference. Different manufacturers can designate terminals differently.
Please read the manual that is provided with the new thermostat. Make sure there is enough bare thermostat wire exposed to get a good connection on each terminal & that it is snuggly secure when tightening.There may be a small switch on the back of the thermostat ( or may have to program ) to indicate the type of heat your system uses. Confirm what you have and adjust accordingly.
Standard thermostat wiring color code
1. ( R ) terminal - Red wire
The red wire is the power coming in from the transformer. Some t-stats require a jumper between " RC " which means red cool, to " RH " which means red heat. Sometimes you have to make this jumper, or often there will be one from the factory already installed.2.( Y ) terminal - Yellow wire
The yellow wire provides power to the compressor contractor. This turns on the condenser.3. ( G ) terminal - Green wire
The green wire provides power to energize the indoor blower motor.4. ( W ) or ( W / Aux ) terminal - White wire
The white wire provides power to the electric heat strip located in the air handler. This may be the only heat source if you have a straight cool AC or it provided supplemental heat if you have a heat pump.5. ( C ) terminal - Blue wire.
This is the common wire. It completes the electrical circuit to provide power to a digital thermostat. If the is no blue wire for you to connect, it is likely the thermostat needs batteries installed to power up the display.6. ( O / B ) terminal - Orange wire
The orange wire is used only if the system is a heat pump. It provides power to energize the reversing valve in the condensing unit outside. Also in the thermostat programming or on the back of the thermostat, there may be a switch O/ B that determines how the t-stat controls this voltage. Rheem and Rudd units, for example, require this to be set on " B " to operate correctly. Most other brands will be set to "O ." If the thermostat is installed and the thermostat is set to cool, but the heat comes on. There is a good chance the setting is incorrect.This wiring is for a single stage air conditioning or heat pump system only. If you have a higher end unit with multiple stages or if it is a variable speed/inverter style unit, a specialized thermostat may be needed, and the wiring is completely different.
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