Did Mice Damage Your AC Unit Through Winter?

May 12, 2022

You’re probably aware of the havoc that winter can wreak on HVAC systems. Frigid temperatures, frost, and moisture are only a few things that can damage your AC or, at the very least, affect its performance. 

But have you ever thought about the damage that mice can cause? These hardy and agile creatures are known for their ability to get into just about any nook and cranny, including household appliances and fixtures. This includes your air conditioning system, which may be harboring a few rodents without your knowledge. 

Why mice enter air conditioners 

Why do mice enter air conditioners in the first place? The simplest answer is: “because they can.” The various openings in the typical AC unit and any cracks and seams around it are irresistible for rodents, which are always looking for places to nest, store food, and avoid predators. 

Once they are in there, mice often find the warm and dark interior of the AC system conducive to their lifestyles. The constant flow of warm air, the relative safety of the shelter, and the restrictive confines provide a secure environment that most would like to stay in for as long as possible. 

How to tell if there are mice in your AC 

The first time you catch sight of a mouse exiting your air conditioner, you can be certain that one or more of them have been there a while. Most homeowners are unaware of the presence of these pesky creatures until after they first see them. But you can be reasonably sure that mice have checked in by the following signs: 

• Odd noises when the AC is off 
• Mouse droppings on the ground below the exterior unit 
• Animal noises from the inside of the exterior casing
• Unpleasant odors from the vents or casing
• Ants or other insects trailing in and out of the AC  

Issues caused by mice in AC systems 

As you may have guessed, having mice live in your air conditioner isn’t ideal. Plenty of things can go wrong when rodents decide to drop in, whether for a weekend or the long-term. 

One of the most common issues that can arise is damaged wiring. Mice are notoriously voracious and will chew through almost anything incessantly, whether it is edible or not. And when that happens, it’s only a matter of time before the wires are exposed and short circuits or component failures occur. 

Mice can even block off vents by piling up random objects in the interior of your AC unit. Whether it is foam, insulation, or hay they gather from outside to build their nests, these materials can cause your AC to overheat, spew out unpleasant odors, and possibly even cause your system to break down eventually. 

What to do if mice take up residence in your AC 

The first and most obvious step is to get rid of the mice currently living in your AC unit. Commercially available traps placed strategically around access points should reduce their population somewhat, but you should take measures to ensure that they don’t come back. 

Make sure to clean your air conditioner regularly to give mice fewer reasons to return. You might even place a few rodent repellent pellets in and around your unit, but be extra careful about leaving them where pets and children can pick them up. 

Once you are reasonably sure that your air conditioner is mice-free, block off any holes or cracks in the installation opening. You can usually do this without affecting your unit’s performance. The key is to make your air conditioner less accessible to any mice that happen to come by looking for a place to stay. 

Hiring an HVAC technician  

Hiring an HVAC specialist to check your air conditioner and get rid of pesky rodents isn’t necessarily the most cost-effective solution. Still, it will almost certainly get your system back to “as-new” condition. When all else fails, this could be the best way to solve your mice problem for good. Plus, you get the advantage of having a qualified specialist check for minor issues that could worsen over time. This could save you a lot of money on costly repairs and replacements.  

J.A. Bertsch

J.A. Bertsch Heating & Cooling offers professional residential air conditioning services throughout Kootenai County. Our licensed A/C technicians cover all of North Idaho and our neighboring cities. Experience superior, award-winning service 24/7. Call us at 208-715-9694 to schedule an appointment.