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What Happens if You Don’t Replace Your Furnace Air Filter

thermometerHow often do you replace the air filter in your furnace? Were you even aware that your furnace had an air filter before you read this? If not, that’s alright. Plenty of people don’t realize that their furnace has an air filter. What’s important is that you take proper action now to keep the filter in good shape. If you don’t, you could find yourself spending thousands of dollars in repair and replacement costs years earlier than you otherwise would have to.

Why It’s There

You may be wondering how important the air filter can really be, if you’ve gone this long without changing it and the system apparently works fine. The air filter actually has a pretty significant role in keeping the furnace healthy, though. The filter is installed in the return duct, so that all air flowing into the furnace must first flow through the filter first. The filter collects dust and debris that might otherwise make it into the furnace and cause problems. It does this job pretty well, but it has one major drawback: it can’t get rid of the debris that it collects. This is why the filter needs to be cleaned or replaced every few months.

Short Cycling

If the air filter is not serviced often enough, it will eventually become clogged to the point that air cannot pass through it. When the furnace is operating, the lack of air flow will trap the heat in the system. As the temperature inside the system continues to rise, the limit switch will activate and shut down the furnace to prevent it from overheating. This will temporarily mitigate the issue, but it won’t solve the root problem. Without a new air filter, the furnace will overheat every time it starts up again. This is referred to as short cycling.


Prolonged short cycling causes a wide range of problems for the furnace. The output of the system drops, due to the lack of air flow. The wear and tear on the furnace increases significantly, causing more frequent breakdowns. If not corrected in time, the lifespan of the furnace could be shortened by a number of years. If you notice your furnace turning on and off every couple of minutes, turn it off and call for repairs immediately. The faster you can get the system repaired, the better off it will be in the long run.

Of course, the whole point if this post is to make it clear that you’d save quite a bit of frustration if you just changed the air filter every few months. This prevents it from becoming clogged in the first place, making it much less likely for short cycling to occur. If you’re not sure where your air filter is located, call a professional and they should be happy to show you.

PRK Services, Inc. offers comprehensive furnace maintenance and repair services in Corinth, TX. Contact us today to schedule an appointment with one of our expert technicians. We’ll make sure that your furnace serves you well.

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