Don’t Let Bugs & Rodents in Your HVAC Vents Spoil Your Summer

ByMarc Silberberg


Summer’s here, and for many of us that means no school and vacation from work. Some folks love the outdoors, don’t mind the bugs, go camping without a care and a tick bite doesn’t throw them off. With portable sleeves and their insect repellents they are off for warm weather adventures such as boating, swimming, hiking, or some more extreme fun.

On the other hand, many people are weary of the summer outdoors since they cannot take the bugs and allergies that appear haphazardly to bother them. These individuals will go from their air-conditioned homes to their air-conditioned cars or to the coldest air-conditioned mall in their vicinity to hang out there. For recreation they would rather visit an indoor water park hating to face the summer sun, heat, and humidity that prevails at outdoor pools. Yellow jackets and other various insects flying and crawling around are not their cup of iced coffee.

 If your kids tend to spend the bulk of their day in your air-conditioned abode, who says that your air-conditioned home is free of bugs? You might notice a couple of spider webs in corners of your home, but as a child you were taught that spider webs catch bugs, so you aren’t too concerned. Did you know that insects and other live pests can be hiding in your HVAC system? Yes, these pests can cause your HVAC system to either breakdown or decrease in efficiency.

What Causes Insects to Enter Your Vents?

The inside of your HVAC vents is dark and moist which is a perfect recipe for the activation of bugs and other annoying rodents, and you may wonder how these pests squeeze into your HVAC vents. Your central air goes on and off as temperatures change in your home, and tiny fractures and cracks around the unit appear for creepy crawlers to infiltrate the vents. Some insects, such as mosquitos like to lay their eggs in moist watery areas and if you have any standing water from condensation this will attract the mosquitoes to lay their eggs in that location causing the mosquitos to multiply quickly. Listed below are some pests that like to live in HVAC vents, and you may be surprised that they are not all benign. Your location will determine the types of bugs that will find habitants in your HVAC system and here is a list of some popular ones.


Although most spiders are harmless, there are some that are poisonous and even if they are not dangerous you don’t want a mob of them inside your home. Spider webs that are found outside the home that are spun in between fence railings are G D’s wonder to behold. Even a heavy storm and rain will fail to knock off this beautiful vision that was created by a hard-working spider to trap small bugs. If you see many spiders in your home, that is a problem for the exterminator, but you might have them tightly concealed in your HVAC vents causing decreased efficiency and that is a task for a HVAC specialist to come and seal any cracks in the system.


No one wants even one mosquito to enter their home causing a disruption in your sleep when one of them begins buzzing in your ear. If you have several in your home your family is in for major scratching sessions since no one would think of spraying insect repellent inside the home. Mosquitos are quite small and hard to catch causing nuisances such as viruses which can make sensitive members of your family downright sick!


If you are one of the lucky individuals who think that this word means some kind of water animal, let me enlighten you about these horrible looking creatures that can live up to eight years. The reason they are called fish is because they have scales like a fish with a silvery-blue color and quickly move side by side, looking similar to a fish tail swimming in the water. Most often, they will take up space under sinks, bathrooms, and any damp area of the house such as moist vents of HVAC systems. They have six legs, no wings and are nocturnal creatures.

Silverfish enjoy starchy items such as books and cardboard and can be found in old books that have not been opened for a while in bookcases or draws. If you do find only a few of these creatures then do not become alarmed, and as long as your HVAC system is tightly sealed, they should not cause a problem in that category. However, if they continue to multiply and stay alive in your home you are best bet is to call an exterminator.

Rats & Mice

Insects are one thing, but rodents are in a despicable category all on their own. While many folks will tolerate bugs outside their homes, no one wants rodents anywhere near their home inside or out. Unfortunately, rodents can and will not only enter your home uninvited but can cause major damage to your HVAC unit without you knowing it right on. Rats, mice, and similar pests just love crawling into tight places to cause you lots of expense and aggravation by often building their nests with duct material and any other debris that’s on hand. They will chew through HVAC elements such as the refrigerant lines and will cost the homeowner big bucks to repair. In this case an exterminator will not be enough, but you must call a HVAC professional in to check out the entire HVAC system and clean and repair specific equipment.


These insects use ductwork as nesting places that are cool and dark. Because of their small size they can squeeze through the smallest opening and although they are not on the top of the list of major damagers you may hear them moving through the ducts and can also carry unhealthy viruses.


If your garden or yard is not well kept there is a chance that snakes, will hole up there so play it safe and check for any holes in the yard where snakes can hang out in warm weather. These sliders can find comfort in the condenser units of your HVAC system because of the appeal of the heat. Once the temperature starts to drop, these cold-blooded creatures will look for warmer homes and they could end up nesting in the ductwork of your HVAC system. Heat generated by the condenser system is also a place that they will be drawn to even though when the fan blades start up, they will be killed as well as the blades being ruined.

Raccoons & Squirrels

Squirrels are known to find homes in attics when the weather turns cooler if they have not found an appealing tree to live in. This is enough of an annoyance and a good exterminator can hopefully assist you in their elimination. Additionally, these animals can chew through your ductwork making holes which leads to the warm and cold air escaping adding to already high energy bills.

Sizing Up the Situation on Your Own

A homeowner can first attempt to clean a dirty and moist HVAC unit personally by disconnecting and cleaning it out with a Shop-Vac. Then make sure all noticeable cracks are sealed with foil tape rather than duct tape since it will hold up better from varying temperatures. Another excellent choice is a water-based sealant to close up those holes.

Your vents should be protected by screens which prevent small bugs from getting through while still keeping the air flow normal. If you are handy, you can buy readymade screening and with the right cutting tool cut the screen to the exact size of your vents and then staple the screen piece onto the vent. Caulking around the vent screens is recommended to keep the seal tight.

Final Words

Summertime is a time for chilling out for many folks and there is no better place to be on a nice day than outside in the sun and water. We should be cautious and check out what’s going not only inside our homes when it comes to finding bugs and rodents but also what’s taking place behind the scenes in the HVAC system. While you are enjoying the outdoors these pests are preparing for the coming winter by building nests and ruining the various components of your HVAC system right under your nose without you suspecting anything.

By making sure that your ducts and vents are sealed properly before the infestation begins, makes it easier to maintain your HVAC system and assuring that it is functioning optimally for heat and cooling. Once even small critters enter your system its efficiency will be interrupted and consequently you will have to call in a professional. Make sure that said professional is highly recommended and knows exactly what he is talking about. Unless you are a person with two right hands, it’s difficult to comprehend what the technician is accomplishing. When you hire someone you trust it will make all the difference and the smartest thing to do is to have someone come in regularly to check out your HVAC system before trouble arrives.

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