There are certain times during the year when you need to carry out servicing and maintenance on your HVAC systems. These best times are fall for your heating system and spring for your air conditioner unit. The times outside those required maintenance schedules when the unit is not operating are a source of confusion for some homeowners. The main concern is whether they should cover their external air conditioning unit when the weather turns colder. Let’s look at this topic in more detail; we will explain when and why you need to cover the unit during the winter months.

When You Need to Cover Your External AC Unit

Many homeowners believe that they need to cover their external air conditioning unit for the winter months. This is incorrect, it is important to protect the unit during the early fall only, and the unit will be fine uncovered during the winter. The cover is not needed to protect the unit against rain or other inclement weather conditions. The external AC unit is not designed to keep out the debris, nuts, seeds, and leaves that are everywhere when fall arrives.

During the fall, the various natural materials seem to get everywhere, and it can be hard to clear them away. This is particularly true inside the external air conditioning unit, and leaves or other debris can easily get inside. These natural materials rot down, and they attract moisture to the internal surfaces and components of the unit. Over time this moisture will cause corrosion damage, and the debris can clog up any moisture drainage measures that your unit is equipped with.

Many homeowners forget about their air conditioner system during fall, and they get a nasty surprise when they need to use it in summer. An uncovered external AC unit can corrode quickly at this time, and vital components can be affected. This can lead to unnecessary repairs, or in extreme cases; a replacement may be required. Prevention is better than the cure, so it makes sense to cover the unit during fall.

How Do You Cover the External AC Unit?

Many people believe that they need to cover the entire external air conditioning unit to protect it during fall. This is incorrect; it’s only necessary to cover the top of the unit to keep out the fall related natural debris. It’s easy to make your own cover, make sure it fits the top of the unit and extend it down by 6 inches for plenty of protection.

Many stores sell covers if you don’t have the time or skills to make your own, but make sure they don’t cover the whole unit. If you cover the entire external AC unit, you actually trap moisture inside, and this leads to the same corrosion issues that we mentioned earlier. It’s important to keep debris and rain out, but the unit still needs to “breathe” to allow any trapped moisture to escape naturally.

Why is a Cover Needed?

During the colder months, we often cover many outdoor related items, such as lawn furniture, grills, and swimming pools, to protect them from the elements. This is particularly true if there is no storage shed, garage, or basement area to store the items until the warmer weather arrives. For some reason, many homeowners believe that this same principle applies to their external air conditioner units. These units require a top cover to protect them, but this protection is required during fall to keep out certain materials. There are many reasons why a cover isn’t needed for the rest of the year.

Dirt, Debris, and Leaves

We mentioned these briefly above, but these materials can cause a number of problems in your external air conditioner unit. When the AC system is turned on, the external unit sucks in fresh air, and this also draws debris into the system. When the unit is turned off, no material is drawn in, and there is no need to worry about damage caused by dirt, debris or leaves. The main cause for concern should be the moisture that these fall related materials will create inside the external unit.

Cold Winter Weather

We don’t need to worry about snow here, but colder winter weather can bring heavy rainfall, and many people worry about their external AC units in these conditions. These units are designed to be located outside the home, and they can withstand even harsh winter conditions. There is no need to protect the external AC unit from the cold.

Accumulated Moisture

If rain gets into the external air conditioner unit, it doesn’t represent any immediate danger. But, if the water freezes on the condenser coils, it can cause damage that won’t be apparent until you get the unit serviced in spring for summer use. Another problem is a build up of moisture that could cause a significant amount of corrosion to the external case and components. There is no surefire way to keep 100% of the moisture out of the external unit, and some will inevitably get inside. The humidity comes from the surrounding air, the wind, and any rainfall. This is why it’s important to allow the unit to “breathe” to let the moisture escape. Covering the entire external unit will trap the moisture inside; this will cause corrosion, and it will encourage the growth of toxic mold that’s hard to eliminate later. For this reason, it’s actually a better idea to not cover the unit at all rather than covering it entirely.

Rodents and Other Pests

Covering your external AC unit will discourage rodents and other pests from entering the unit. In fact, the exact opposite is true, these creatures are looking for somewhere warm and dry to see out the colder months, and a covered unit is an ideal spot for them. These pests can find there way into very tight spaces, so if your external unit is uncovered during winter, it’s a less attractive proposition to choose the area as their winter home.

In Summary

It’s only necessary to cover the unit in fall, and only the top of the unit needs to be covered. Always get your air conditioner checked in spring, and your heating checked in the fall to make sure the equipment is ready to use. Finally, always choose a professional HVAC technician to work on your system to protect your investment.