Animals and insects can cause major damage to your exterior air conditioner unit. Keeping an eye on the unit ensures you catch damage early before major repairs are needed.
Your dog may be your best friend, but they aren't a good friend to your air conditioner. Dog urine is corrosive, and it can eat through metal and cause damage to the housing and evaporator fins on the outside of the unit. If your dog spends a lot of time wandering around your AC and you notice rust on the fins, housing, or the bolts that hold the housing in place, then urine may be to blame. The exterior housing may need to be replaced and the fins repaired if rust has already occurred.
Rodents typically move into an AC unit in the fall, after the unit is shut down for the season. The pests are seeking out a warm, dry place to set up their winter nests. Nesting materials can clog the blower fan, while rodent droppings are corrosive to the parts inside the AC. Further, rodents often chew through electrical wiring. Repair entails cleaning out the unit and then replacing corroded materials and repairing any damaged wiring.
Another corrosive problem is bird droppings. Bird droppings are extremely acidic. They tend to collect on top of the AC unit, and they may also drip into the blower fan if the top of the unit is the fan vent. Eventual corrosion will eat holes into the housing's finish and it can also cause the fan to suffer damage. Repair requires cleaning off the droppings and in some cases refinishing the housing to repair the damage. The fan can usually be cleaned and lubricated, unless the damage is so extensive that the droppings have already eaten into it. In this case, you will need to replace the blower fan.
A variety of insects can invade the AC. Ants are a common issue in some areas, as they will build ant hills both around and inside the unit. These giant ant nests will interfere with the function of the unit, and in some cases, ants may enter electrical components and cause shorts. Bees and wasps may also sometimes build hives in a unit, particularly in early spring before you begin using the AC for the first time. As long as no permanent damage is done to the wiring, the only needed repair is to clean out the nest or hive.
Contact an AC repair technician if you spot animal damage on your unit.