Should you cover your central air conditioner in the winter?
As temperatures drop, many homeowners are wondering whether they should be covering their central air conditioning units.
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Do you need to cover your central AC unit in the winter?
In theory, it makes sense to protect it from the elements in winter, particularly here in our Canadian winters. But the truth is that air-conditioners were built to handle all the conditions they may face outdoors without a cover. They have built-in drainage to get rid of rain and snow melt, so contrary to what you may think, outdoor AC units don't actually need additional protection during winter months.
Rather than protecting it, covering your air conditioning unit during winter can do more harm than good. It can trap moisture and condensation in the unit, which can lead to mould. The warm spring weather before you get the cover off can also pose a hazard by creating a superheated greenhouse that can increase the vapor pressure inside the lines as the liquid refrigerant begins to boil. What’s more, snug, air-tight covers can be very appealing to critters looking for a spot to cozy up during cold winter months, and the last thing you want is mice or other rodents making a nest in your AC unit and eating your wiring for a snack.
If you are still determined to cover your air-conditioner despite this advice, a custom made metal cover to cover the top only is the best option. This allows the unit to “breathe” while keeping debris out of the only opening at risk of falling leaves and the like. A good metal cover should be secure enough to not come off in the wind and pose a hazard, but come off easy enough that if you forget to remove it before starting your air conditioner in the spring it can blow off the top with just the force of the fan.
Whether you cover your unit or not, it is a good idea to turn off the disconnect before winter so that when you turn it on in the spring it forces you to at least have a look at the unit while doing so.
