What you will learn in this article:
1) What thermostat wire color is likely to go to which terminal on the thermostat
2) The function of each wire terminal on the average thermostat highlighting some of the differences in those functions from manufacturer to manufacturer
Sometimes the thermostat is not the problem. Please check this article for a checklist of things to check before calling a heating and cooling repair service.
Thermostat Wire Colors Code | HVAC Control
Thermostat Wire Colors Code – Always follow the thermostat manufacturers instructions whenever changing the thermostat. Always turn the power off at the air handler and the condenser and make sure there is no voltage at the transformer before proceeding. The thermostat wire colors below are the most likely colors used for most installations however your thermostat wire colors may be different than what is indicated here. There is no official standard for thermostat wire colors. Thermostat wiring colors are not standardized but these are the most wiring methods used based on my years of experience in the HVAC field where I successfully wired a lot of thermostats.
Honeywell Thermostats Available Here
For instructions on how to wire a thermostat please see our how to wire a thermostat page.