When dogs decide to mark their territory on your air conditioner, it can be quite corrosive to your unit and can result in:
FINS: The fins help to improve the energy efficiency in the AC by increasing the surface area of the coil. Increased surface area allows the coil to get rid of the heat faster. When the fins are damaged or missing, it can lead to higher AC bills. If only a small area of aluminum fins (less than 25%) are damaged and the coil is not leaking, you may want to leave your AC alone for now. The fins are important for increasing energy efficiency, but losing a few of them will not make the unit inoperable. You may just notice a higher energy bill because your AC unit is working harder.
CONDENSING COIL: The job of the condensing coil is to get rid of the heat your air conditioner absorbed from inside your home. Extensive damage could lead to the coils leaking.
Replace the coil if the damage to the coil is greater than 25% and the following is true.
Replace the entire outdoor AC unit if at least one of the following is true.