When should I be covering my air conditioner?

There are a couple of reasons that it is not that important to cover your air conditioner, even in the winter. The most important reason is that it is not really necessary. Here’s why: what you might not realize is that all outdoor HVAC equipment is made to withstand harsh weather conditions and varying temperature extremes. That is what they are made for, and is actually part of the reason that your air conditioner is so damned expensive.

All of the parts and materials used are designed to stand up to hot summers and harsh winters. There are some caveats to this, of course, and those will be addressed in the next section. It should suffice to say, that no major manufacturer that I know of (i.e. Carrier, Lennox, etc.) specifically recommends that you cover your air conditioner in the winter.

To verify, we went ahead and gave a few of the major air conditioning companies a call to see what their take was on whether or not you should cover your air conditioner in the winter. Upon calling their customer service departments, they also said that there was no specific instance in which they would recommend that you cover your AC unit for the winter. Think about it – you’d better believe that if covering your air conditioner in the winter was making a significant difference in the longevity of your air conditioning unit, then the major companies would not only recommend it, but they’d probably provide you with a cover as part of your purchase.

There are a couple of other reasons that it is not desirable to cover your air conditioning unit, many of which might not be that obvious to you:

1. Rodents Can Infest Covered Air Conditioners
Rodents and other animals seek shelter from harsh winters and will often start to inhabit a covered air conditioner. This can lead to secondary problems like chewed electrical wires and un-insulated Freon lines due to the rodents stripping them to make a nest.

2. Mold and Mildew Can Grow Inside, if You Cover Your Air Conditioner in the Winter.
Mold can accumulate in the spring months before the air conditioner is uncovered due to the increased moisture inside. Your air conditioner is made to be open to the air. Covering your air conditioner will block proper air flow which can lead to mold growth on your evaporator coils. While mold growing outside of your home is not detrimental to your health the way that it is inside of your house, it can block proper airflow through your coils and decrease your air conditioner’s efficiency. For more information, try: How Do You Prevent Mold?

3. Covering Your AC Doesn’t Prevent Moisture From Infiltrating Your AC Unit
Probably the biggest argument that can be made for why you should cover your air conditioner in the winter has to do with water. If water accumulates on your air conditioners external coils (called condenser coils) and then freezes, it runs the possibility of damaging your coils over time.

Although this is a valid argument, the problem is that covering your air conditioner doesn’t really solve this problem. Moisture will get in and accumulate either from humidity that is naturally in the air, or from wind blowing it in. As the water on the ground evaporates, it can also find it’s way in. The bottom line is that covering your air conditioner doesn’t do a very good job of keeping moisture out of your unit. It will find its way in eventually.

When Should You Cover Your Air Conditioner?

Cover Your Air Conditioner for Hail Storms
If you live in Santa Clarita, then it is not really necessary to cover your air conditioner – ever. But for those of you who are up north, it might be worthwhile to cover your air conditioner under some circumstances. For instance, it is not uncommon in the midwest to encounter hail. Although it is not possible to predict, if you know that a large convective storm is coming, give some though to covering your air conditioner before the thunderstorm gets there (key word being before, not during the storm – stay inside).

Cover Your Air Conditioner for Blizzards
The same advice should be used for those that live up in the north – if you know that a blizzard is headed your way, then take a few minutes to cover your air conditioner. Keeping the excess snow out of your air conditioner can help quite a bit, specifically if the temperature warms up to above freezing temperatures during the day, then drops below freezing at night. If the snow accumulates inside of your air conditioner, then melts and refreezes, you are essentially making a mini glacier inside of your air conditioner which can damage your coils. Cover your air conditioner before a blizzard, and uncover it right after. Take a few moments to remove the snow right around the outside of your unit and it will pay dividends in the long run.

As a general rule of thumb, I’d offer the following advice: imagine your old diesel truck – if the weather is bad enough that you would worry about your old diesel, then it’s time to cover your air conditioner. If your diesel could handle it, then you’re AC is all set.

How Do You Cover Your Air Conditioner?
Like we discussed above, unless you live in extreme weather, it isn’t really important that you take the time to cover your air conditioner in the winter. However, if you do, there are a couple of ways to do it.

The first way is to use a large tarp and wrap your air conditioner using rope and duct tape. This, as you might imagine, can take 15 minutes each time that you do it. It’s not worth it. The second way, is to go online and buy an air conditioner cover. They are relatively cheap, and range from around $25 to $35. If you are going to go to the trouble of covering your air conditioner in the winter, then you might as well do it right.