As the sweltering summer sun starts to fade and the cooler temperatures of fall starts to settle in, residents of Portland start preparing their homes and yards for the wintertime. For many, that leads to the question of whether they ought to cover their outdoor air conditioning unit for the winter.

While it may seem like a smart idea, the reality is there are several reasons why you shouldn’t cover your AC unit in the winter. In addition to not being necessary, covering your outdoor air conditioning equipment can sometimes cause problems.

Here, the specialists at Three Rivers Heating & Cooling share five reasons why covering your AC doesn’t need to be on your fall to-do list and what you should do instead.

1. Your AC Unit Isn’t Damaged by Snow

Exterior AC units are designed to withstand harsh weather conditions like snow in the wintertime. These units are built with sturdy materials and components that can handle the outdoor elements without damage. The coils and fins of the unit are engineered to resist corrosion, and the housing is designed to protect the internal elements from moisture and debris.

2. Covering AC Systems can Encourage Mold

One of the reasons you should not cover your AC unit in the winter is because doing so can trap moisture—which is definitely not what you want in your outdoor unit. That’s because allowing moisture to collect inside the unit creates the perfect conditions for mold and mildew to spread.

Mold and mildew not only have an unpleasant odor, but they can also create health risks, especially for individuals with respiratory issues or allergies. Plus, the trapped moisture can corrode the internal components of the AC unit.

As an alternative to covering the unit, instead make sure the unit has proper drainage and keep the area around the unit clear of debris, allowing for efficient airflow and preventing moisture buildup.

3. A Covered Air Conditioner Can Host Animals

Human beings aren’t the only ones who make plans for winter. Animals that live around your home are also looking for a warm, cozy place to crash for the cold months. For many critters, a covered air conditioner is the perfect winter home.

Birds, mice, chipmunks and even rats commonly make nests inside covered air conditioners. Animals living in a covered AC unit can cause many problems. Rats can chew through wires, insulation and other components, causing damage that may require expensive repairs. Debris animals bring into the AC to make themselves a warm and comfortable place to get out of the cold weather can impair airflow and ventilation, lowering the efficiency of the appliance and potentially causing it to overheat. Additionally, animal droppings can result in unsanitary conditions and potent odors.

Leaving your air conditioner uncovered helps deter wildlife, because an uncovered AC gives them less shelter from the elements than a covered unit. That’s better for your cooling system—and leaves you with less mess to pick up and things to repair when winter is over.

4. An AC Cover Restricts Airflow

Another reason you shouldn't cover your air conditioner in the winter is because a cover blocks airflow through the unit. Suitable airflow is essential for the AC system because it facilitates heat exchange and permits the unit to cool efficiently. When airflow is reduced, the system has to work harder to maintain the desired temperature, leading to greater energy consumption and strain on the components.

In addition, if you use your air conditioning without noticing that the outdoor unit is covered or because you simply forgot, it could result in a range of problems. One issue is that the absence of appropriate airflow could cause the compressor to overheat, resulting in its failure or damage.  That’s why it is necessary to ensure the outdoor unit has no barriers and is not covered to maintain the best possible airflow.

5. AC Maintenance Works Better Than Covering Your Air Conditioner

The bottom line is, it's lots more effective to do a little maintenance for your cooling system than to cover your exterior AC unit.

There are several key maintenance projects you should prioritize to ensure the best possible operation and longevity of your AC unit. First, it’s a good idea to look at your outdoor AC unit regularly and remove any debris such as leaves, small branches and dirt to allow proper airflow. Second, examine and clean the coils, fins and filters to make sure they are free from dirt and dust buildup that would prevent effective heat exchange or airflow.

Routine air conditioning maintenance not only boosts efficiency, but it also helps extend the unit's life span, decreases energy consumption and prevents costly repairs. Rather than using a cover, putting time and effort into routine air conditioning maintenance is a proactive plan of action that can substantially benefit your entire HVAC system in the long run.