Rodents are often drawn specifically to the heating system in order to find a place of refuge from the cold. For that same reason, rodents like to nest in ductwork. They will chew on whatever they can find. When they begin to feast on HVAC electrical wiring, your home’s safety is compromised. Chewing through a wire can lead to an electrical fire and a damaged HVAC system. When rodents find their way into your ductwork and make nests or leave droppings behind, tiny fecal spores are swept along by the force of heated and cooled air moving through the ducts. These spores make their way into your home and contaminate the air quality.

Seal your ducts

Gaps, cracks, and larger disconnections in the duct system create points of access for pests to enter your HVAC system as well as your home or building’s interiors. Insects, mice, and larger vermin may enter the duct system, depending on the size of air leaks. Ductwork should be professionally sealed and you may elect to treat your home with pesticide to prevent re-infestation. Duct cleaning can not remove dead pests but can remove debris they’ve left behind to improve indoor air quality.

Install flue and vent covers

Your HVAC system utilizes flue pipes to expel byproducts of combustion from the furnace; these pipes must be in good working order to protect occupants from dangerous carbon monoxide poisoning. Vent covers should be installed on all exterior flues, intakes, and exhaust vents. These covers will block pests’ point of entry, preventing them from traveling inside your home or business, and keeping your pipes clear of nests. These covers have additional benefits, such as keeping rainwater out of your vents. Make sure vent covers are installed securely; small animals can be resourceful and may find a way to pull off your covers if they are not on tightly.

Protect your air conditioning condenser

Rodents and other small animals can cause great damage to your exterior air conditioning condenser. They can damage components by chewing, scratching, urinating, and more – even their presence can harm the system, should you happen to turn the air conditioning system on when they are inside. Your best line of defense in protecting your condenser is preventing rodents from coming near it, to begin with. Keep the area surrounding your condenser clear by cleaning around it on a regular basis. Cutaway vegetation and clean excrement, which can attract rodents to the area initially. Warm water and a mild soap can be used to scrub and clean the exterior of the unit as well as the surrounding area.


Depending on how long the rodent damage has gone on, the cost to repair the damage can vary. Eventually, the damage to your system will likely cause it to malfunction, and you’ll need to call a repair contractor. If you schedule annual service, your HVAC technician will be able to identify rodent activity early on.