WHAT IS A C-WIRE? A C-wire, or a common wire, runs from your low voltage heating system (24v) and carries continuous power to your thermostat. In today’s electric market, most newer heating and cooling systems have C-wires, which guarantees compatibility for the installation of all smart thermostats.

How do I know which wire is the C wire?

Quote from the video:
Quote from Youtube video: So it's fairly simple to tell if you have a/c wire or not firstly the purpose of a/c wire is basically for the newer thermostats. As either has a backlit display or has Wi-Fi functionality.

What color is the C wire?





Blue wires

Blue wires are also called “C” wires because they are the Common wire. C wires are necessary for any “smart” thermostat that needs to be connected to a power source 24/7, regardless of your heat pump type.

How do I know if I have a blue wire or C wire?

Take your existing thermostat off the wall — it’s usually easy to do — and turn it over. You’ll see wires of many colors, and one of those might be blue. If so, look at the terminal to which it’s attached, and you should see the letter C. The blue wire, or C-wire, is known as the common wire.

Is the red wire the C wire?

It is most often either blue or black, unless the installer did their own rewiring to create a C wire. These are the most common colors and the labels used for thermostat wires: Blue or Black – C – The common wire. Red – R – 24 VAC power from the transformer in your furnace.

Where is the C wire on my furnace?





Quote from the video:
Quote from Youtube video: The wire coming from outside from the condenser unit is only going to have two wires a red and a white looking like this. And those two are going to go to y. And c common on that terminal strip.

What if there is no C wire for thermostat?

If your current thermostat didn’t need a C-wire, it (or a wire that can be used as a C-wire) might be rolled up inside the wall. This is more likely to be true if you see all the other color wires present. Line voltage thermsotat scenario: you have just two wires (white and red, probably), and they’re thick.

What color wire is the common wire?

Red wires are hot wires common in a 240-volt outlet or when a wall switch controls the outlet. Blue and yellow wires are hot wires for ceiling fans and three- or four-way switches. White or gray electrical wires are neutral wires.

What color is o’b wire?

O stands for orange and B for dark blue.



The O and B terminals are for heat pumps; the B terminal is used in conjunction with Rheem, Ruud, or any other manufacturer that energizes the reversing valve in the heat pump’s heating mode.

What color wires go to condenser?



Quote from the video:
Quote from Youtube video: So the color code we usually use W. That's white why. And that's yellow G. And that's green or. And that's red and C is usually blue.

What is the C wire on a thermostat?

What is a C-Wire? A common wire (C-Wire) provides Wi-Fi thermostats continuous power by connecting it to a heating and cooling system (e.g. furnace). C-Wires are required on most Honeywell Wi-Fi thermostats, with the exception of the Smart Round Thermostat (formerly known as the Lyric Round).

Where does the condenser wire go?

The condenser may be fitted outside the distributor, or inside on the contact-breaker baseplate; on a few cars it is fitted into the wiring somewhere near the distributor.

How do you wire up a condenser?



Quote from the video:
Quote from Youtube video: This brown wire right here says F or fan and that one goes to the fan that's on the top of the outdoor condenser. All.

What are the wire color codes?

3-Phase Wire Color Codes

  • Phase 1 – Black wire.
  • Phase 2 – Red wire.
  • Phase 3 – Blue wire.
  • Neutral – White wire.
  • Ground – Green, Green with a Yellow Stripe, or Bare Wire.


What are the 3 connections on a capacitor?

On many systems these terminals may already be labeled so that the three leads on a start/run capacitor can be wired correctly:

  • S = start wire connector.
  • R = Run wire connector.
  • C = common connector.



How do you wire an HVAC compressor?

Quote from the video:
Quote from Youtube video: It goes to the herm or to H that's labeled as H on the capacitor. So we know that the blue wire goes to herm. And the wire going to the capacitor is always going to be coming from your start winding.

What is the black wire on a AC compressor?

The black wire, leading to the load side of the contactor, is connected to the run terminal. The white common line is connected in series with an overload switch that protects the compressor from overheating. The overload might be internally located in the compressor.

How do you identify start run common terminals of compressor?

Quote from the video:
Quote from Youtube video: Now it's fairly simple in order to determine. Which terminal is what so we're gonna go ahead and just take these off. And just explain how this goes.