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Repair & Maintenance

Don't Let These Pests Damage Your A/C

Warm temperatures result in dependency on air conditioners. Before your A/C unit malfunctions, make sure to have it inspected and protected from pests, like mice.

Pests in HVAC

Air conditioning is a must for many homeowners during the warmer months of the year. A nice cool house is always a welcome respite from the high temperatures and humidity outside, especially in parts of the country where summer heat may not subside until October.

When your home's air conditioning begins to fail, you need it fixed quickly and professionally. American Home Shield® warranties cover timely repair or replacement of your A/C unit due to normal wear and tear, but sometimes the problem is more significant. If your A/C unit fails due to interference by mice, snakes or other pests, AHS warranty protection will not cover the damage.

What types of pests can damage an air conditioning unit?

A number of different critters that crawl, slither, gnaw or build mounds can cause trouble with your air conditioning system, both inside and outside of the house.

  • Mice and rats like to crawl into small spaces, and they can harvest air duct material to build their nests. These rodents can also chew through refrigerant lines, electrical wires, and other A/C components, leading to expensive repairs and potential hazard.

  • Snakes can nest in ductwork or sometimes coil up in the condenser. A snake that is inside the A/C unit when it turns on up will likely be killed by the motion of the fan blades, but that interaction can also damage the blades or other components.
  • Termites, ants, wasps and other pests may also make their way into your A/C system. Ant mounds can keep parts of the unit from operating properly or short out electrical connections. A wasp nest in an air vent can also be dangerous, particularly if anyone in your family is allergic to wasp stings.  

Can mice get through air vents?

Mice are small and flexible enough to get into many tight spaces, including air ducts. The Centers for Disease Control (CDC) warns that mice can squeeze through a hole as small as a nickel and that rats can get through a hole as small as a half-dollar.

  • Interior air vents that have louvered, angled or grid openings smaller than a nickel in size will likely not allow enough room for a rodent to squeeze through.
  • Fresh air intake vents and exterior air vents can be entry points if they are large enough, are cracked or there are holes in the protective screens.
  • Attic and crawl space vents are also easier for mice and rats to access if not properly screened or covered.

Rodents in air ducts and vents pose health risks to humans. Some people can have allergic reactions to mouse and rat dander, urine or droppings. Wild rodents can also carry a variety of pathogens that may cause diseases, so it’s important to carefully check your A/C system for any signs of their presence or have a professional pest control technician inspect it.

A dead mouse in the ductwork might be the source of a foul odor that lingers or worsens when the A/C unit is in operation. Dead mice may even have to be removed before the situation improves.

What about snakes?

Snakes can also slither into exterior air vents when the reptile in question fits through the available vent, crack or hole in the screen. This is not the most common air conditioning problem, but it’s best to keep snakes away from your A/C unit and system.

To discourage snake activity, make them feel less welcome in your yard.

  • Mow and weed regularly, and don’t let areas of tall grass develop.
  • Fill any holes in the grass or dirt that might give snakes a place to hide.
  • Sprinkle sulfur powder — a snake deterrent — around the edges of the yard.

Pest-proofing air conditioning units, ducts and vents

Pest-proofing is an important part of air conditioning maintenance. Preventing outdoor critters and nesting insects from accessing and damaging the A/C unit — or interfering with the wires and lines that connect to it — is a key to keeping the system in good working order.

  • Install air vent and flue covers. Use mesh screens or special coverings made for air vents and flue pipes to help keep mice, wasps and other pests out.   
  • Seal air ducts. Make sure pests cannot access air ducts through cracks, gaps or holes in the ductwork. Repair ducts promptly when a problem is discovered and replace duct tape if it is peeling due to consistent or extreme temperature changes.
  • Protect the condenser. Keep the area around your exterior A/C unit clean and clear of vegetation that could attract mice or snakesLook for signs of feces, urine or chewing, especially along refrigerant lines and electrical wires. Watch for the beginnings of ant mounds.
  • Cover air vent grilles and protect air ducts. Vertical louvers will help prevent birds and insects from nesting in or around vents and ducts. Mesh or specialty screens will also help keep all manner of rodents out.
  • Reduce moisture around the A/C unit. Get rid of rain or condensation puddles that may form near the unit. Standing or dripping water can attract mice, rats, snakes and other critters.This can also create conducive conditions for termite activity.
  • Use appropriate pest control measures to prevent infestation. Contacting pest control professionals who are properly trained is the recommended way to ensure that you are using appropriate pest control methods to prevent infestations.

Prioritize Your Pest-Proofing Routines

An effective way to help prevent pests is to start with a routine and stick with it.

Help Prevent Pests By Sticking To a Routine

  • Maintain your A/C unit on a regular schedule.
  • Have the system checked by a professional once a year. Make sure the technician cleans the components and looks for signs of pest activity in the condenser, vents and duct system.
  • When repair or refurbishment is needed, don't put it off. Commit to keeping your A/C unit in top shape so that it will cool efficiently and last longer.

If you do find a dead mouse in your ductwork or a pest infestation in your A/C unit, consult a professional pest control service. Contact our friends at Terminix® today to learn how they can help remove rats, snakes and other pests from your home.

Attention to pest-proofing now can help avoid a host of uncovered repairs later. Whether your A/C unit needs a repair or a replacement due to normal wear and tear, American Home Shield® provides warranty services that you can count on. American Home Shield® Home Warranty plans cover up to 21 major components of systems and appliances including your A/C, heating, plumbing, refrigerator, oven, stove and more.

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