If this is the case, then you'll need to find the fan limit switch and move it back into automatic mode. This will ensure that your furnace fan runs only when necessary and not continuously. The fan limit switch is typically located near the blower motor or in the control box.
Problem 1: Incorrect thermostat settings The most common reason for a furnace fan that won't shut off or a furnace blowing cold air and won't shut off is the wrong thermostat settings. The solution: Check the thermostat settings. The fan setting should be on AUTO. If it's set to ON, the furnace fan won't shut off.
You should see a little white button/knob, this is your fan limit switch. If that white button appears to be pushed in, the switch has been set to manual override, which means the fan will run constantly. By simply pulling the white button out, you'll reset the switch to AUTO mode.
A fan may continue to run even when the furnace thermostat is off for several reasons: Fan Limit Switch Setting: The fan limit switch controls the operation of the fan. If it's set to run continuously or if it's malfunctioning, the fan may continue to operate even when the heating system is off.
Most furnaces have a reset button near the blower compartment itself, though the exact location may vary depending on the make and model. It's usually red or yellow and small in size. Consult your furnace manual for guidance if you're unsure where it is.
A bad thermostat can also cause the fan to run continuously or not turn off when it should. To ensure your thermostat is functioning correctly, it is recommended to consult with HVAC Alliance Expert's specialists.
To find the limit switch on your furnace, look for a red, yellow, or white button on the panel. To restart your furnace manually, hold this button for three seconds before releasing it. After restarting the system, affix your control panel back on the furnace and turn your furnace back on via the circuit breaker.
If your thermostat is not working properly, it may not be able to accurately read the temperature in your home or properly communicate with your furnace. This can cause your furnace to run continuously, even if your home is already at the desired temperature.
Running it continuously may lead to more frequent maintenance and repair needs. However, the added comfort and air quality benefits often outweigh these concerns. Noise: If you're sensitive to background noise, you might find the constant hum of the furnace fan bothersome.
This isn't necessarily bad for your fan, but it is usually a sign of a bigger problem. Common causes for fans not turning off when they should include faulty thermostats, bad wiring, and stuck relays. These problems are not easy DIY repairs and should be left to an HVAC professional.
One way to know that the limit switch has a problem is if your furnace keeps going on and off throughout the day. Usually, when the blower is overheated, it trips the limit switch causing the furnace to shut off even before the cycle is over.
"Most electrical fans are designed to be able to run continuously for several hours at a time, for example overnight or during the day, but you'll also need to keep in mind doing that continuously for long periods can cause wear and tear on the motor and other components, shortening its lifespan," continues David.
The fan limit switch controls when the furnace blower fan turns on and off. This control also provides a safety limit that turns off the burner or furnace if temperatures at the furnace get too high. Fan/Limit switches are used on all types of heating furnaces.
A furnace limit switch is a component of a forced-air furnace that is responsible for turning on the furnace blower once the desired heat has been met inside the furnace. Without a functioning furnace limit switch, a furnace would not be able to regulate the temperature in conjunction with a thermostat.
If this is the case, then you'll need to find the fan limit switch and move it back into automatic mode. This will ensure that your furnace fan runs only when necessary and not continuously. The fan limit switch is typically located near the blower motor or in the control box.
One reason why your furnace blower won't turn off is because of incorrect thermostat settings. For instance, the blower will continue blowing if the settings are higher than what your furnace can achieve. This is because it will continuously heat the space in an attempt to reach the set temperature.
First, turn off the power supply to the furnace by turning off the breaker in the circuit box. Locate the reset button on the furnace and press it to reset the furnace. It is usually located inside the blower compartment on the side of the blower motor. Be cautious, as the housing may be hot.
First of all, be aware that not all furnaces have a reset button; however, most do. If your electric furnace has one, it's most likely located within the blower housing, next to the motor. If you own a gas furnace, it's probably located within the control panel. Check your owner's manual for specifics.
Remove the furnace access panel to locate the high limit switch on the outside of the plenum. Unscrew the switch from the plenum. Use steel wool or sandpaper to gently clean away soot and other materials stuck on the rod. Replace the switch and access panel.
The first and simplest check is to make sure your thermostat is set to AUTO rather than ON. If it's set to ON, change it to AUTO. This should allow the blower fan to shut off within just a few minutes. If that doesn't do the trick, the next possibility is that the thermostat is set to an overly high temperature.
Running the Fan Continuously
This offers benefits for your home such as: Improved air circulation throughout your living spaces. Enhanced indoor air quality by filtering air continuously. Reduced motor stress by minimizing frequent starts and stops.
If the cooling fan relay has failed, you may see warnings, such as the check engine light and the temperature warning light, pop up on the dash, but first, you may notice that the A/C stops cooling. More about that in the next paragraph. The check engine light illuminating may indicate a faulty cooling fan relay.