Are you supposed to change the furnace filter in summer?

Author: Dr. Casimir Crist DDS  |  Last update: Wednesday, May 28, 2025

Changing the filter in summer, however, should definitely be a regular monthly event. Here's why: In most areas of the country, the central air conditioner runs longer cycles and more hours during the typical summer day than the furnace runs in winter.

What happens if you don't change the furnace filter?

Air filters that are overdue for a change are a common cause of HVAC system failure. Over time, dirt builds up in the heating and AC filters, causing components such as the motor to go into overdrive, which may eventually overheat your unit.

Why is my furnace filter dirty after 2 weeks?

Your filter gets clogged faster when your furnace is running more often. That's because more air is cycled through your filter when your furnace goes through more heating cycles, so more contaminants get caught on the filter's media. The colder it gets outside, the faster your filter will get clogged with dirt.

How often do you really need to change a furnace filter?

For 1- to 2-inch filters, replace them every 1 to 3 months. For 3- to 4-inch filters, replace them every 6 to 9 months. For 5- to 6-inch filters, replace them every 9 to 12 months.

Does the AC use the furnace filter?

While many people refer to air conditioning and furnace filters as if they're different, this is not the case. Your furnace and your air conditioning system use the exact same filter, so there's no need to worry about purchasing separate filters for each piece of equipment.

Furnace Air Filter - How to Change It Properly

Do I need to change my furnace filter in the summer?

No matter which way you look at it, changing your furnace filter during summer benefits you in a number of ways. Don't let the clogged furnace filters affect the working of your HVAC system or defile the air quality in your home, no matter what the season.

Can I run my AC without a furnace filter?

The short answer: You can get away with running your AC without a filter for a short period of time. However, doing so for longer than 6-8 hours can hurt your system and decrease your home's indoor air quality.

How can I tell if my furnace filter needs changing?

Signs Your Furnace Filter Needs Changing
  1. There is noticeable discolouration on the filter.
  2. You can see the buildup of dirt and dust.
  3. You find your home needs dusting frequently.
  4. It seems your HVAC system is cycling longer.
  5. You realize it's been several months since you've replaced your filter.

Can I run my furnace without a filter for a day?

Your furnace can, technically, run without a filter. However, we strongly recommend you don't run your furnace without a filter for any length of time. With air constantly moving through your furnace and your home, dust and debris can quickly build up, even in a matter of minutes.

How do I know if my furnace filter is too dirty?

If the filter is still in good condition, light should shine through. If the filter is dirty or clogged with debris, the light will be obstructed, indicating it's time for a replacement. The presence of visible mold is another one of the dirty HVAC filter symptoms that indicates it's time for a replacement.

What happens if I put my furnace filter in backwards?

The most common problem you will face with a backwards facing filter is simple inefficiency. If your furnace is forced to blow air through the non-porous end of a filter, it will take more energy to do so. The blower will be overworked and you will pay more money for your heating.

Will my furnace shut off if filter is dirty?

If your filter becomes clogged, it can cause your furnace to shut off as a safety feature to prevent damage to the furnace. To fix this problem, simply replace your air filter on a regular basis. If you have pets, be sure to change your air filter more frequently.

What happens if you leave your furnace filter in too long?

If you leave your furnace filter in for too long, it can become clogged and make your furnace work harder to circulate air. This can lead to increased energy consumption and can potentially damage your furnace. Additionally, a dirty filter won't be as effective at improving air quality.

Can I clean my furnace air filter instead of replacing it?

Cleaning an air filter only has two additional steps from replacing one. Again, the first step is to turn off the HVAC system. Find the service panel, open the furnace, and then locate your filter and remove it from the furnace. From here, you'll want to place it dirty side up and gently vacuum the large debris.

How many hours does a furnace filter take?

These particular types may not last as long as other individual components, but they can be cleaned and reused for a longer time frame. Replacement filters vary in their lifespan from model to model. However, these usually need replacement every three months or after 200 to 300 hours of usage.

Do I need to turn off furnace before changing filter?

Changing a furnace filter is simple. First, make sure your furnace is turned OFF so it doesn't blow air when you remove the filter. Next, locate the filter housing on your furnace. This is different for each model, but you can normally find it between the air intake and the furnace.

Is it better to have a dirty furnace filter or no filter?

For a furnace to work properly, it should always be equipped with a clean, working filter. As we'll see, a dirty filter can cause problems, and so can having no filter at all. When it's cold outside, many of us rely on furnaces to heat our homes.

Why is my furnace not blowing hot air?

If your furnace is not blowing hot air, or is not operating at all, a component called the fan limit switch or high limit switch may have malfunctioned. You may also see an error message on your thermostat, or a blinking LED light on the furnace control board.

Can you vacuum a furnace filter?

Taking care of your furnace filter is all part of regular maintenance. There are some key variables you will need to be able to keep your furnace filter going strong: Wash or vacuum the filter once a month. Many filters have a minimum efficiency value rating.

Why is my air filter black after 2 days?

Black Soot Deposition

Black soot can quickly turn our air filters black. This is usually a result of burning candles. Candles are made of carbon-based materials that don't all combust when burned. They end up producing tiny soot particles which then get into our carpet, on our furniture, and in our air filters.

Does changing the air filter improve AC?

Some people ask: Will changing the air filter help the A/C? When you change your air filter, you improve your home heating efficiency along with its ability to cool. When it comes to wondering, will changing the air filter make it cooler, yes.

What does a dirty furnace air filter look like?

The filter may look clogged or matted, with visible clumps of dust and hair. You might see dark streaks or spots on the filter, which is a sign of heavy buildup. The filter's pleats or fibers may appear flattened or compressed. However, it's due to accumulated debris that has built up in the pleats.

Why is AC not blowing cold air?

First, check your filters and coils for dirt and debris that may be impeding airflow. Once you've cleaned the filters and coils, run the air conditioner with just the fan so that the ice accumulation can melt off. If the AC still doesn't blow cold air, it could be that refrigerant levels are too low.

Does your AC run through your furnace filter?

Air Filters

Even though the furnace is not producing any heat while operating the a/c, it still delivers the cold air throughout your home with the same blower, and passing through the same air filter. This is why, regardless of the season, you should regularly change your air filters.

Will a furnace run with a dirty filter?

A dirty filter in your furnace will generally lead to the following consequences: The furnace can overheat and turn off as a failsafe. Your home won't achieve the warmth or comfort you want. You can severely damage your furnace's internal components.

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