An AC filter is one of the most important, yet often overlooked components of an HVAC system. Its main function is to trap and hold any contaminants and particulates in the air that circulates through your HVAC system. This ensures only clean and fresh air is released into the room, improving indoor air quality and protecting your family’s health.

However, over time, your AC filter collects massive amounts of dust and dirt. This causes your HVAC to strain, as well as other issues that could affect your indoor air quality and its performance. Regular AC conditioner service can help keep the air filters in the best condition, ensuring your AC works as efficiently as possible.

Here are the top signs to help you know the right time to change your AC filters to prevent costly repairs and keep your HVAC system running cleanly and efficiently:

1. An unusual increase in your electricity bill

high electric bill due air filter

One of the main signs you need to have your AC filter changed is when you notice an increase in your energy bill. Your home’s cooling and heating needs account for a large portion of your monthly electricity bill. Your electricity bill could increase due to heavy use of your AC, especially during the summer months when the heat strikes. However, if you notice a spike in your electricity bill, the cause could be a poorly functioning AC system.

Accumulation of dirt in the air filters makes them clogged, hindering proper airflow. This makes your AC work harder to manage the interior temperature, increasing your carbon footprint and a higher electricity bill. Replacing the dirty air filters with clean ones can help your AC work more efficiently, significantly reducing your energy bill.

2. Dusty surfaces near the air vents

Another common sign it might be time to change your AC filters is the buildup of dust on furniture and surfaces near the vents. When air filters become clogged with dust and dirt, over time, the dirt gets into the unit, releasing it into the room through the air vents.

Examine the area closest to the vents for the presence of dust and debris. Compare the amount of dust on surfaces near the vents with other areas farther away. Alternatively, hang a white cloth near the vents for at least one hour to determine if your AC filters are clogged. If the cloth turns gray, the air filters are dirty and you should consider changing them immediately.

3. Suffering more allergy attacks

dusty air filter

When your air filters become clogged, your AC accumulates and releases different contaminants and pollutants into your house, leading to poor indoor air quality. Breathing air saturated with pollutants can make you suffer frequent allergy attacks and experience symptoms like headaches and nausea. As such, you should consider changing your AC filters immediately after you start having more allergy attacks and symptoms associated with poor indoor air quality.


Not only can a dirty or damaged air filter lead to poor indoor air quality, but it can also reduce your AC’s efficiency. This can increase your risk of developing various health problems, increase your electricity bill, and also lead to costly breakdowns. Use these tips to help you know when to change the air filters and keep your AC operating properly and efficiently.

Signs that you need to change your AC filter was last modified: October 6th, 2022 by Billy Guteng
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Do not forget curious noises. Oh God! Once I thought a rat entered the air conditioning and it was because it had a bad motor or something like that…