Understanding and Interpreting Furnace LED Codes

You use the LED code on your furnace to get readings on the performance of your system. But what do all those red, green, and blue lights mean? Understanding the meaning of these codes is important because they can alert you to potential problems with your system. Low voltage codes are usually red, medium voltage is usually yellow, high voltage is usually green, and a code that flashes at a constant rate is a warning sign. What does each code mean? Understanding the code on your thermostat or humidifier will let you know if there’s something wrong with it so you can get it fixed as soon as possible. If you have questions about any of these codes, give us a call!

Furnace LED Code – Red Light

The red light on your furnace means that the voltage is low. This is one of the most common furnaces LED codes. If you see this light come on, there is a problem with the power supply to your furnace. If the voltage is too low, the furnace won’t be able to turn on. But why does the voltage drop? This can happen when there is a power outage in the area, and the power company has to shut off the power to protect the grid. If it is raining heavily and there are thunderstorms in the area, there’s also a chance that the voltage could drop too low. If there are problems with your home’s wiring, it could cause a voltage drop. If you see a red light on your furnace, turn off the circuit breaker to the furnace and call a professional to check out the system.

Furnace LED Code – Green Light

The green light on your furnace is a warning sign and not an error code. This light indicates that the blower wheel has stopped rotating. If you see this light on your furnace, something is blocking the blower wheel. This could be a piece of lint, dust, or something else. If you see this light come on, turn off the circuit breaker, unplug your furnace, and clean out the blower wheel. If you can’t remove the debris, call a professional to inspect the blower wheel.

Furnace LED Code – Blue Light

The blue light on your thermostat or humidifier indicates an error with the temperature setting. If you see this light come on, your thermostat or humidifier has detected an error. This could be because the wires are crossed or because the thermostat is worn out and needs to be replaced. If you see this light come on, turn off the circuit breaker, unplug the device, and call a professional to inspect the thermostat or humidifier.

Furnacing LED Code – Flashing Red Light

The flashing red light on your furnace indicates that the voltage is too high. If you see this light come on, turn off the circuit breaker, unplug your furnace, and call a professional to inspect the system. If the voltage is too high, it could cause a fire.

Furnace Thermostat Code – Flashing Green Light

The flashing green light on your thermostat indicates that the device is out of calibration. If you see this light come on, turn off the circuit breaker, unplug the thermostat, and call a professional to calibrate the device. If your thermostat is out of calibration, the furnace won’t be able to turn on when you want it to.

Humidifier Codes – Flashing Blue Lights Together and a Flashing Single Blue Light

The flashing blue lights together on your humidifier indicate a dirty humidifier. If you see this light come on, turn off the circuit breaker, unplug the humidifier, and clean out the humidifier. Call a professional to inspect the device if the light keeps coming on after you clean out the humidifier. The flashing single blue light means that the water level is too low. If you see this light come on, turn off the circuit breaker, unplug the humidifier, add water to the tank, and restart the device. If the light keeps coming on after adding water to the tank, call a professional for help.

Bottom line

Furnaces use a variety of lights and sounds to provide information about the system’s state. You’ll see an error code on your thermostat when something goes wrong. These codes can vary depending on the type of furnace you have, but they’ll help you figure out the problem and what steps to take next.