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Furnace Fan Won’t Turn Off: What’s Wrong?

a house where the furnace fan won't turn off

Is the blower fan on your furnace running continuously? When the furnace fan won’t turn off, several different things could be causing it to keep running. It’s a good idea to address this or contact professional help quickly. A constantly running blower fan is not just a waste of electricity. It’s also a signal of a potential problem with your heating and cooling system.

Check Out the Problem

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. This can cause the blower fan to run continuously as the system tries hard to bring your home to the desired temperature. To rule this out, try manually setting the thermostat to a temperature several degrees lower than the room temperature and wait a few minutes.

If the blower fan shuts off, double-check that the system is still set to AUTO, set the thermostat back to the desired temperature, and go on with your day. But if the fan continues to stay on despite these troubleshooting measures, there may be one of several different issues happening.

The limit switch on the furnace fan may be set to Manual. You can check on this yourself if you are a handy DIY type. Go to your furnace and remove the panel cover. You should see a white button that controls the limit switch, and it should not be pushed in. The switch is currently in Manual mode if the white button is pushed in. It needs to be reset to Automatic mode for the furnace fan to stop running constantly.

What’s Causing This?

If the limit switch is set to the correct mode yet the fan is still running, the limit switch could be faulty. In this case, a heating and cooling specialist will need to replace it.

If the system set the switch to Manual mode, it may mean that the furnace overheated. This can happen when the air filters are clogged. Clogged furnace filters cause reduced airflow, which makes the furnace work too hard. Ultimately, the system can overheat. Keep in mind that furnace filters need changing every three months, on average. If you live in a home with shedding pets or in an area with lots of dust or pollen, you might need to change yours out more frequently.

Closing too many of the vents in your house can also cause the system to overheat. It’s a good idea to keep the vents open so every area of the home can heat up evenly. This will make your home more comfortable and help prevent the furnace from overheating.

If the limit switch isn’t the problem that’s causing your furnace fan to run continuously, it’s also possible that the wiring to the thermostat has shorted out or gone bad. Alternatively, the thermostat itself may have failed. Both of these are issues that are best addressed by a professional.

A few other possibilities can cause a furnace fan to run continuously. When the simple troubleshooting steps don’t resolve the issue, it’s best to contact a reputable heating and cooling specialist for help. An HVAC professional can diagnose and fix the problem both efficiently and safely.

This will ultimately save you money in the long run. Running a malfunctioning heating and cooling system takes a lot of extra electricity. This is why it’s a smart idea to set up regular maintenance checks with a professional. A pro can keep your system in top shape over time, lowering your energy bills while lowering the risk of an expensive problem developing in the future.

An HVAC pro working on a furnace in which the fan is not working

Furnace Fan Not Working: What to Look Out For

You may notice a few different symptoms when your furnace fan is not working properly. The most obvious symptom is when the furnace turns on, but there is no heat. This could mean the furnace’s blower fan has stopped working. But, a few other indicators can point to this same problem.

A loud clanking or clanging noise coming from the furnace when the fan starts blowing is another immediate and obvious sign of something wrong with the fan. In most cases, when this happens, it’s due to bent or damaged fan blades. The fan can get damaged when debris makes its way into the system. The bent blades then bang against the casing and make loud noises.

If you hear this type of noise coming from your furnace when the fan turns on, it’s best to turn it off as quickly as possible and contact a professional. A heating and cooling specialist can repair or replace the damaged fan quickly.

A subtler sign of a furnace fan that’s not working correctly happens when you notice your electricity bill getting unusually high. When this happens, it can mean your heating and cooling system is working too hard. Broken or malfunctioning components make the entire HVAC system struggle to heat and cool your home. This results in higher energy bills. Higher bills are often an early warning sign that something is going wrong within your furnace. The furnace fan could be the culprit.

Ruling Out Other Issues

It’s also a good idea to rule out other issues altogether. For example, it might seem like the furnace fan isn’t working, when really the whole furnace isn’t turning on due to a tripped circuit breaker. If you go to the circuit breaker box, check to make sure the breaker for your furnace is switched to ON.

Your furnace fan won’t turn on if the thermostat is set to a temperature lower than the room temperature. Set the thermostat to something higher than the air inside the home.

Clogged air filters can also cause furnace fans to stop working properly. These filters need changing every month or so. When they become too dirty and full of debris, they seriously reduce airflow through your heating and cooling system. This can overheat the furnace and affect other components, including the blower fan.

When you notice any signs that indicate your furnace or its blower fan aren’t working, it’s a good idea to call in a professional to inspect the system. An HVAC specialist has the training and tools to inspect every heating and cooling system component to determine which parts are failing and why. They can then make the needed repairs quickly and efficiently, so your home can return to a comfortable temperature as soon as possible.

a living room in which the furnace is blowing lukewarm air

Furnace Blowing Lukewarm Air: What to Do

When it’s cold outside, you rely on your furnace to keep your home warm and cozy. But sometimes, the furnace runs but doesn’t seem to work properly. It might blow cool or lukewarm air instead of the warm air you expect. When you find your furnace blowing lukewarm air when it should be blowing hot, there are several possibilities for what’s going wrong.

Checking Out Your System

First, make sure your thermostat is actually set to Heat and not Cool. If it’s on the wrong setting, the system can’t provide the house with warm air. You should also make sure it’s set to AUTO, not ON. When the blower fan is set to ON, it will run continuously. When the fan is set to AUTO and the system is set to Heat, warm or hot air should blow out of the vents.

It also helps to know a bit about your home’s heating system. Gas furnaces tend to produce hotter air blowing out of the vents. The air generated by a heat pump won’t be quite as hot. If your home has a heat pump, it’s not a problem if the air blowing out of the vents doesn’t feel as hot as you expected, as long as the system does bring the home to the desired temperature set on the thermostat.

Sometimes, the furnace fan blows air while the furnace’s heating components shut off. This happens when the furnace has overheated, which is often due to clogged or improperly installed air filters. There could also be a problem with your HVAC system’s heat exchanger, gas supply or flame sensor.

These are issues best handled by a heating and cooling specialist with the required training and tools to fix the problem. It’s also a good idea to sign up for regular maintenance visits with an HVAC professional. Having your home’s heating and cooling system serviced regularly saves you money in the long run. A pro can spot problems and head them off early, saving you money on your utility bills.

ABC Can Make Your Home Comfortable Again

Without a functioning heater or air conditioner, the members of your household can quickly get uncomfortable. If you’re having issues with your unit, contact ABC Home & Commercial Services. We can make HVAC system repairs, provide preventative maintenance and can even offer honest advice on when to replace your air conditioner.

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