Demystifying Thermostat Wiring Colors – What Goes Where?

If your space is centrally air-conditioned, a thermostat definitely comes in handy. The thermostat helps you regulate the temperature of the room and makes it comfortable for you to adjust according to the weather outside. There are times when you might have to install the thermostat on your own.

With the manual handy it might seem easy but when it comes to adjusting the color-coded wires it’s all the more difficult. And in case you put the wires in a wrong coded manner, it can lead to malfunctioning of the thermostat.

Almost all thermostats available in the market have some color coding to follow. There are a few general settings that they usually follow.

You can read the color codes below to have a rough idea about what they infer.

Red Wires – R Terminals (Power)
Yellow Wires – Y Terminals (Cooling)
White Wires – W Terminal (Heating)
Green Wires – G Terminal (Fan)

These are what generally the Demystifying Thermostat Wiring Colors actually mean more or less.

But before you start to work to set the thermostat wiring make sure the main transformer is switched off and so is your thermostat. There should not be any power flowing through the blower or condenser.

Now let’s look at Demystifying Thermostat Wiring Colors, what they represent, how to identify them, and connect them in the right coded manner.

1. Red: There are 2-3 terminals with which you can connect the red wire. In the split systems, usually, a red wire comes down from the transformer itself. The transformer is in the air handler or in the condensing unit for a few systems.

And as the red wire is connected to the transformer, make sure all power is cut while handling the thermostat.

The red wire is also used for the RC terminal which is used to provide power for the cooling unit. And the counterpart for the RC terminal is the Rh terminal which is used to source power for the heating unit.

2. Yellow: As the yellow wire is used for cooling, hence it is used to control the air-conditioning.

3. White: The white wire is used for heating. The wire originates from a heating source such as a furnace, or a boiler.

4. Green: The green wire is connected to the fan. It is connected to the blower fan.

Remembering these color codes can help you attach the wires correctly. If you mess up the color codes it can lead to malfunctioning of the thermostat and the entire air conditioning of the room. You need to follow these color codes and where their terminal and original ends should be connected in order for it to function properly.