What Should You Do When Your HVAC Fan Won’t Turn Off?

The most popular season in Michigan is summer. According to a survey of residents, it’s followed by fall, spring, and winter. The extreme cold and sub-freezing temperatures might be the reason winter ranks last on the list.

Thankfully, a working HVAC system can ensure you’re comfortable regardless of the temperature outside. It should provide proper ventilation to reduce humidity and regulate indoor temperatures. It also helps to remove contaminants in the air to maintain indoor air quality.

If your HVAC fan won’t turn off, these functions can be compromised. Certain signs will indicate if this is the case. It’s important to know what they are, why they may be happening, and how to fix the problem.

You’ll have a better insight into all the above after reading this article. It will also provide tips that can help you prevent fan issues. Read on to learn more.

How Does Your HVAC Fan Work?

The HVAC fan removes air from your home and sends it through your heating and cooling units. Once at the desired temperature, the fan filters the air and then redistributes it into your home.  

The thermostat prompts this process and ensures the units and fan work together. When set on “auto” the fan and the cooling and heating units turn on at the same time. When the air reaches the desired temperatures, they all turn off.

In most HVAC systems, the fan may run a few minutes before the heating and cooling process begins and ends. This helps to get the air flowing. Otherwise, your HVAC fan should not be running unless you turn the thermostat on.

Signs Your AC Fan Isn’t Working Properly

You’ll see your HVAC fan running when you look through the panel guard of your condenser unit. You’ll also hear it. Besides these obvious signs, here are a few others that may point to an improperly working fan.

Increased Utility Bill

An HVAC fan, if left running, will use approximately 360-kilowatt hours (kWh) per month. Michigan’s electricity rate is approximately 19.5 cents per kWh. That’s an additional $70 per month you’ll be spending.

Harder Working Unit in Summer

During the summer months, a continuously running HVAC fan will blow hot air into your home. Your AC will need to work twice as hard to cool the air.

This may also result in dirty, more humid air entering your HVAC system and eventually circulating throughout your home.

Colder During Winter

An HVAC fan that won’t turn off may blow cooler air through your vents during winter. Your fan will keep running even when the furnace isn’t producing heat. During these periods, it will circulate cold air.

More Filter Changes

You may also find you have to change your filter more often. A constantly running HVAC fan will continue to blow air across the filter.

This occurs even if your system isn’t heating or cooling the air. The filter traps more dirt, causing it to get clogged more frequently.

Reasons Why Your HVAC Fan Won’t Turn Off

Does leaving your HVAC fan running have any benefits? Some people believe it does. These include cleaner air, faster circulation, and reduced humidity during the winter.

However, if you’re concerned about energy efficiency, you probably won’t want your fan running continuously. If it won’t turn off, here are a few reasons why.

Thermostat Settings

There could be an easy fix for a continuously running HVAC fan if it’s due to your thermostat settings. The fan won’t turn off if your thermostat is set to “on”. When set to “auto” your fan will turn off once the room reaches the desired temperature on the thermostat.

Faulty Thermostat

Your HVAC problems may not be due to a broken HVAC fan. You could have a faulty thermostat. Your thermostat may stop sending the correct signal to your fan due to low battery power.

It can also stop detecting the correct temperature because the sensor is faulty. The HVAC fan will continue running if the thermostat is experiencing either of these issues.

Extreme Temperatures

Extreme cold or hot temperatures can make your HVAC system work harder. This keeps the fan running as it works to get to the desired temperature.

Poorly maintained or undersized systems often create this problem. This can also occur if you try to lower or raise the temperature by more than 20 – 25 degrees.

Short Circuit or Broken Relay Switch

An electrical issue may also be causing your HVAC to keep running. A broken relay switch won’t respond to the settings on the thermostat. This can also occur if there is a wiring problem or short circuit.

Troubleshooting An AC Fan Constantly Running

Before repairing your HVAC, troubleshooting can help determine what the problem might be. Here are a few things you can do:

Check Your Filter

A clogged filter can result in poor air quality, dirty vents, and higher energy bills. Your system may also take longer to get cooler or hotter. It will also cause your HVAC fan to stop working properly.

You can locate your filter between the return duct and the air handler. A lot of dust and debris will be evident if it needs changing.

Check Your Thermostat

Several thermostat issues may affect how well your HVAC fan works. Here’s how you can determine which, if any, is at the root of your HVAC fan problem.

Thermostat designs vary, so you may need to check your manual to ensure you have it on the right setting. However, most thermostat displays will indicate if it’s set to “on” or “auto”.

You should also check the thermostat’s battery to ensure it’s fully charged. Once replaced you may need to reset it. When doing so change the setting to “auto”.

Finally, you should set the thermostat temperature lower than the room temperature. Doing this should turn the fan off. 

Check Your Circuit Breaker

An HVAC fan that won’t stop running may be a symptom of a bigger problem. Your entire HVAC system may not be working properly due to an electrical issue. Check your circuit breaker box to ensure the circuit for your HVAC is turned on.

Check Your Fan Limit Switch Setting

You can locate the fan limit switch under the hood of your furnace. It controls when the furnace fan turns off and on. There is a white knob on the switch which, when pressed in, is set to manual override.

This causes the furnace fan to keep running. Pulling the white knob out resets it to “auto”. While in this setting, the fan turns off when the furnace reaches the desired temperature.

Call a Professional

A professional can determine if the issue is due to a faulty thermostat sensor. They can also check for any electrical problems.

If you’ve followed the list above and your HVAC fan is still running, it’s best to call a reputable HVAC company. They’ll get to the root of the problem.

Preventing Fan Issues

Some HVAC issues can be due to the age of your system. Others are easily preventable with regular maintenance.

HVAC Tune-ups

Regular tune-ups can help keep your system in optimal condition. This involves an inspection to check for signs of wear and tear. The technician will also check to see if your refrigerant is low.

These tune-ups can help detect any issues your system may have. This can help prevent any major or permanent damage.

The frequency of your HVAC tune-ups should depend on the age of your HVAC system. Have units five years or older checked twice a year, while an annual tune-up is sufficient for newer units.

Cleaning and Maintenance

You should also have your HVAC system cleaned and maintained.

Experts recommend doing this at least once a year. This will include thoroughly cleaning the elements, coils, and drains.

During this yearly maintenance, the technician will check the thermostat functionality. They will inspect the connections and motor operations. They’ll also replace any broken or non-working parts.

Fixing Issues immediately

If you detect a problem with your HVAC system, have it repaired immediately. Any delays might make the issue worse.

Living in discomfort longer than necessary may not be the only price you pay. Repairs may end up costing a lot more.

Troubleshooting may identify the issue, but resolving it will require a professional. This is particularly important if your system is making unusual noises. A strange smell can also be a sign of something more serious.  

You should replace your thermostat if it’s over 10 years old.

Maintaining Your Comfort in Any Weather

What’s the key to staying comfortable in any type of weather? Appropriate clothing and an HVAC system that works efficiently. If your HVAC fan won’t turn off, your HVAC system won’t work well. There may be several reasons this could occur.

Aspen Heating and Air Conditioning can find out why. e have expert technicians and we offer 24/7 support. We will ensure your comfort isn’t compromised in any season because our customers are our number one priority. Schedule your HVAC service today to prevent future issues.