Don’t Let Fido Pee On Your Air Conditioner

Do you have a dog who likes to mark his territory? Fido is likely housebroken, but few homeowners address outdoor urinating habits. At most, they may yell at their pooch to not pee in the garden. If Fido marks your home's central air conditioning unit, though, he is shortening its lifespan.

Male Dogs Mark Air Conditioners

While any animal, including female dogs and all cats, may urinate on your air conditioner, male dogs are most likely to pee on it. Male dogs are territorial, and they mark their territory by urinating on objects. Should multiple dogs be in the same area, they will often repeatedly mark the same object in order to claim it as their own.

Male dogs may mark any object. Commonly marked objects around homes include trees, bushes, fences and fire hydrants -- along with air conditioners. A little urine on most of these objects does not cause any serious harm, but dog urine can quickly damage an air conditioner.

Dog Urine Corrodes Air Conditioner Fins

Dog urine corrodes air conditioner fins, which are the thin pieces of metal on the outside of your central air conditioner that let air flow into, through and out of the unit.

Fins from sites like are typically made of aluminum, and, according to K-9 Kondo, dog pee causes aluminum to rust. (This is why K-9 Kondo makes dog crates out of zinc-plated steel, instead of aluminum.) Thus, every time Fido marks your air conditioner, any urine that comes into contact with your air conditioners' coils is accelerating their corrosion.

The damage caused by dog urine is often difficult to notice for a couple of reasons. First, the rust is located on the lower portion of the air conditioner, because dogs are only a few feet high. Even large breeds can't reach the upper part of the unit.

Second, the corrosion is often only in a few little spots. Droplets of urine are not large, and the rust they cause is not a lot. It can be serious, though.

The Damage Can Be Serious

Initially, the damage caused by Fido's territorial instincts will not significantly impede your air conditioner's performance. The fins are supposed to let air flow through, and a few pinholes in them will have a negligible, if any, effect.

If left unaddressed, however, your air conditioner's fins will become more and more corroded. Eventually, Fido's urine could eat right through the fins and reach the air conditioner's interior. If the pee causes coils inside to rust, your unit could leak freon. (Freon is the coolant used in air conditioners.)

This would take years to develop, but it would be a significant problem. A freon leak would need to be repaired by a professional HVAC technician.

Prevent Fido From Marking

Don't wait for the rust to become an issue. Instead, find a way to prevent Fido from marking your air conditioner. You might:

  • train Fido to not pee on the unit
  • place a shrub near the unit for Fido to mark instead
  • build a run for Fido away from the unit
  • put up a decorative fence around the unit

The last of these three options would prevent all neighborhood dogs, not just your Fido, from marking your air conditioner. They might mark the fence, but at least that won't rust like your air conditioner's fins.

If you have a dog that is marking your air conditioner, don't wait until his urine corrodes the unit's fins. Find a way to stop the habit soon, whether through training Fido, planting a shrub, building a run or putting up a fence.  A little effort now could save your air conditioner from rust and an expensive repair.