Sometimes, mice can be cute little critters. Sometimes they can be annoying vermin who invade your home. The hidden sections of your air conditioning unit can be tempting for mice, and if they decide to make themselves at home here, this can result in a rather annoying problem. So how do you know if you have mice inside your air conditioning unit? And what's the easiest way to fix the problem?
You will probably be able to hear mice inside your air conditioning vents, even if you can't see them. The clicking of their claws on the metal surfaces of the vents can be quite noticeable. You should inspect the immediate interior of the vents directly behind the wall grilles. A torch might be sufficient, but you might need to remove the grilles with a screwdriver in order to perform a more thorough inspection. Look for mouse droppings in the vents and also droppings that might have been pushed up against the filter by the force of the air. Hearing the mice and then discovering their droppings is about the most conclusive way of knowing that mice have moved into your air conditioning unit.
You need to identify and block the likely points of access. Closely inspect the outside component of any split system air conditioners. Check the access panels. Have they come loose? Tighten them as needed. You should also check the intake vents. Depending on the manufacturer of the unit, there might easily be enough space for a mouse to enter the unit via this section when the unit is turned off. It's difficult to seal this point of entry without impeding the air intake capabilities of the unit. A more foolproof method is to construct a barrier around the exterior component of your split system air conditioner. You would essentially need a wooden box frame covered in fine wire mesh on all but two sides, looking much like a chicken coop. One of these empty sides would sit on the ground so that the unit can be enclosed, and the other empty side would be pushed up against your home. It can be attached to your home with a caulking sealant. This will prevent any creatures from accessing your unit without affecting its air intake. But what about the mice that are already inside?
You can call an exterminator to get rid of the mice, or you can just open your interior grilles and lay traps. There are a variety of no-kill mouse traps available (which catch the mice for a later release), but these are boxy and bulky, and even if they fit inside the vents, they will prevent the air conditioner from expelling cooled air. It's not a pleasant end for the mice, and yet at least you are getting your air conditioner back and have prevented any other mice from meeting a similar fate.
Hopefully mice inside your air conditioning unit is not something you will ever have to deal with, but with the proper preventative measures you can ensure that it won't happen more than once!