Yes, and this is one of the more frequent causes of service calls. Outdoor condenser units are dry, sheltered, and warm, and that makes them good nesting spots.
Mice like to chew the low-voltage control wiring and insulation found inside AC units. It’s a big hassle because it can cause shorts and failures, not to mention the repair bills needed to fix those things. Rodent incisors grow continuously, so mice gnaw constantly to keep them worn down. Wire insulation is soft, it is at mouse height, and it is right where they are already nesting.
The condenser cabinet is where a lot of this behavior happens. Mice enter through the base openings and gaps around the line set. Then they nest in the bottom of the unit or on top of the electrical panel. Around that nest sit the thermostat and control wires, the contactor wiring, and the insulation on the refrigerant line. All can be easily chewed. Nesting material also packs against the coil and blocks airflow.
When mice set up shop in your AC unit, this usually shows up in the form of electrical issues. The system starts shorting or runs only intermittently. Breakers trip. Then it’s only confirmed once a technician pops open the panel and finds a bunch of shredded insulation and mouse droppings. Sometimes this is only spotted in spring after mice have spent all winter in a unit no one checked.
There are some things you can do to greatly reduce the odds this happens to you. If you have mulch or landscaping near the condenser, pull it back. You want a few feet of clear space. Also move woodpiles, trash cans, and stored items away. Have an HVAC technician seal the gap where the line set enters the house, because that also helps prevent rodents from moving indoors. And check the unit before the season starts and clear any nesting material you find.
Whatever you do, though, don’t put poison in the cabinet. If the mouse eats the poison, then they die inside the cabinet and then you have a different, smellier problem to contend with.
If mice are nesting around your AC unit or your home, Mosquito Squad of Rhode Island can help. Mosquito Squad finds how mice are getting in, clears them with traps and bait stations, and seals the entry points with chew-resistant materials. Annual inspections will help you protect your home over time.
