What Happens if I Don’t Change the Air Filter for My Air Conditioner?

How often do you need to change the air filter

Do I Really Need to Change my HVAC Air Filter?

Most people know they need to change the air filter for their air conditioning system.  How often would say you need to change that air filter?  That’s what we are going to talk about this week on Fox Family Heating Air and Solar.

The Air Filter Basics

Hi I’m Greg Fox, and we at Fox Family are so proud to be able to take care of your HVAC system.  Typically, the filters you buy at the store say to change them every 90 days.  There’s an arrow on those filters that points in the direction of the air flow.  It’s important when changing these out that you follow the instructions on the filter so they work effectively.

Most of us have the one-inch pleated filters that get changed at the return air filter grille in the ceiling or lower on the wall if your ductwork is under the house.  That’s not as common, though.  Others must replace their filter at the air handler itself.  That air handler will be either in your attic, in a closet somewhere, or in your garage.  If you have a newer home, the air filter is usually found in the attic.  Later model homes will have the furnace or air handler in the closet or garage.  You’ll know it if it’s in your closet because you can hear it pretty easily.

If you don’t know where your air filter is, because you just moved in to a new home or you’ve just never thought about what happens if you don’t change your air filter, give us a call here in the Sacramento Valley and we’ll be happy to come out and show you.

The Blower Motor Gets Dirty

The filter is there to keep your air handler and the rest of the system clean.  On most systems around Sacramento, the blower motor and its fan blades are the first thing that will appear dirty if you don’t change your air filter.  That doesn’t seem too important, but if your fan blades get even an 1/8” of dust build-up, your air conditioning system will decline in efficiency.  The motor must work much harder to spin the fan blades because it’s heavier.  This can make your blower either slow down or just quit working altogether.

I’ve seen some blower fan blades so impacted with dirt and other things,that the scoops that make up those fan blades were completely full.  There was nothing to scoop the air and throw it in to the house! Those scoops are only a ¼ to 3/8 inches deep.  So, you can see how a dirty blower wheel can really decrease the air conditioner’s performance.

The Evaporator Coil Can Become Clogged

When we come out to service calls that have a dirty blower assembly, it usually leads to inspecting the next part in your air handler that the dirty air comes into contact with:  the evaporator coil.  This is the cold coil that the blower sends air through to cool your home.  This is a big one, folks!

An evaporator coil is similar to a radiator grille in a car.  It has tubes that go back and forth left to right for about 20 to 30 turns.  Layered in with those tubes are some tightly woven aluminum fins which form a coil called the evaporator coil.  If your blower motor doesn’t get dirty from a never-changed air conditioner filter, this evaporator coil surely will.  There’s just no way for the bigger particles of dirt and hair to get through this coil.

It’s Trouble

The consequences of a dirty evaporator coil are very detrimental to your air conditioner’s proper operation.  Air is supposed to flow through this cold coil at a certain rate and flow, through the ducting system that delivers air to the registers in your room.  If this evaporator becomes laden with dirt it will slow the air down so much sometimes that this normally cold coil becomes a giant ice cube.

The warm air from the house is designed to become about 20 degrees colder when it passes through this evaporator coil.  Slowing down the air flow with a dirty coil can make that 20-degree effect become a 40-degree effect, which in turn reduces the air flow even more.  The coil will eventually begin to quickly freeze into an ice cube!  No more air will get through the system and into your rooms because it’s become a giant ice ball!

A Snowball Effect

Most people turn their system off at this point.  What happens next can damage your system even more!  The ice ball begins melting, and eventually will increasingly melt downwards onto the blower motor where we all know water and electric motors don’t mix.  This does happen frequently and can cause the motor to stop running altogether.

Gross!

This is the air you’re breathing!  Would you like to know exactly what gets caught in these filters and then becomes part of the filters itself?  — dirt from the surrounding air, dander and fur from our pets, flakes of skin from our bodies, hair from our heads and bodies, mold, pollen, grass, and dust tracked into your home from people coming and going all day.

Your house has couches and beds that carry dust mites which leave their microscopic waste in the carpet, which eventually makes it into the filter for your air handler.  Smokers leave their fumes around, which stick very easily to the filter, and common household products like sprays and  cleaning solvents also get drawn into them.

Have you ever wondered why your filter sometimes gets black?  If you burn candles in the house, the smoke from the flame mixes in with the air.  If your air conditioner is on, it sucks that smoky air into the system.  That soot gets lodged into the filter as well, making it black.

We have a lot of wildfires here in California that cause the air to become so thick and harsh to breathe, some people start wearing face masks.  Even if your home’s windows and doors are all closed up, it seeps through the cracks in your home making its way to the filter.

What are some other things you think are getting stuck in these dirty air filters?  Are there local pollutants in your area that inevitably make it to the air filter?  Let us know in the comments section below.  I’ve seen candy wrappers, old air fresheners, cigarette butts, bottle caps and so many other things in there.  It’s absolutely gross!

The Lining of the Ducts and Supply Registers Get Dirty

If you just moved into a house and know that the last tenant there was a smoker, there’s a brown slime very likely lining the inside of the ducting system leading to your rooms.  You may even see brown gel on the registers in those rooms.  If it’s lining the ducts, it’s in your system, and you’re breathing that air as well. Dirty air filters allow small particles of air to pass on into the ducts as well.  I usually refer to it as moon dust, because its so fine.

Dust and Airborne Particulates Mean Poor Air Quality

I like to think of it this way.  If you were to put an air mask on that started out white, and after even just 3 months, it was gray or brown in color from all these things listed above, would you still wear that air mask?  No.  Why? Because that would be disgusting right?  I think it’s the same when we don’t change our air filters for our air conditioning systems.  Click here for a more in-depth look at the air quality in your home and how it can affect your health.

Change Your Filter!

If you buy filters at the store, they usually come white with pleats or ridges to help increase the surface area of the filter.  If that filter isn’t perfectly white, it’s time to change that filter.  This is why I don’t recommend buying the super expensive filters, because people get attached to them, and don’t want to spend that $20 again.  Just get the super cheap filters like I’ve been using at my house for years.  My system is still perfectly clean because I change them so often.

90 Days?

Filters say on the trim to change them out every 90 days.  That can be misleading because in the off season, when its mild outside, we don’t really use our system to heat or cool us.  It’s nice outside.  During these times of the year your filter isn’t getting dirty, so there’s really no need to change them.  But during the hot times of the year we might need to change them once every month or two.  That’s 30 to 60 days.

Here’s how I do it.  I see my return air filter grille every time I walk down the hallway in my house.  Naturally as an HVAC technician, I look up at my filter in the ceiling pretty much every time I pass through the hallway. If I see the filter is not as perfectly clean as it was when I bought it, it’s time to change my filter.

Set a Reminder on Your Phone

Renters of homes and condos are notorious for not changing the filter in their homes. It’s not their system, so they don’t know how or they don’t care about extending the life of the HVAC system because they don’t have to buy a new system if it fails.  So, homeowners and property managers, set yourself a reminder on your phone every 60 days or so to stop by your property and change those filters.  If your not doing it, the tenants don’t seem to be doing it either.

We work for a few property management companies, and the number one call we respond to isn’t a broken-down system, it’s just the filter is so heavily impacted the system can’t breathe right.  If the system can’t breathe in because it’s dirty, it can’t breathe out either.  So just keep that in mind.

Wrapping Up

I really hope this explains what happens if you don’t change your air filter on your air conditioning system.  The filter says every 90 days, but in the summer and winter it might be more often.  Just keep an eye on it and visually make sure it’s always clean.  If you don’t, all you’ll get is mayhem.  Repairs happen.  But, when it’s done out of response for not being maintained properly because of something as easy as changing your filter 4 times a year, that could’ve been avoided.

Leave me some comments down below and let’s start a conversation about this topic.

Thanks so much for stopping by, and we’ll see you on the next blog post.

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1 Comment

  1. Thanks Greg for this great article on filters! I think I need to contact my apartment office to get them to change my filter out!!!


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