Should I Cover My Outdoor Unit During Colder Months?


During the colder months of the year in Boulder, CO, you likely store or cover your outdoor patio furniture, flower pots and barbecue grill. You may wonder if you should cover the outdoor unit of your air conditioner or heat pump during the winter as well. Here’s what you need to know about why covering the outdoor unit is a bad idea almost all the time and when the one good time is to temporarily cover it.

Outdoor Units Are Designed For Extreme Weather 

Even though you won’t be using your air conditioner until late spring or early summer, you don’t need to worry about protecting the outdoor unit from extreme winter weather. It’s designed to withstand all forms of precipitation as well as wind, direct sunlight and occasional dust or smog. The outdoor unit’s housing is made from coated steel, and proper maintenance of the unit is all it needs in order to make it through an intense Boulder winter. If the outdoor unit is part of a heat pump, covering it could shorten its lifespan and result in a system malfunction. That’s because your heat pump will work throughout the winter. If it’s covered, it won’t be able to do its job of absorbing heat from the outdoor air and transferring it into your home.

Improper Cover Materials Can Lead To Rust and Corrosion 

Using a plastic cover or tarp on your outdoor HVAC unit could facilitate the development of rust and corrosion. That’s because plastic traps moisture that’s already on the unit. It keeps the moisture there and stops air from moving around the unit. The moisture has nowhere else to go and can’t evaporate. Constant exposure to moisture and heat could cause significant rust or corrosion of the fan, fins, coil and exterior housing of the outdoor unit.

Incorrect Covers Promote Infestations 

During the colder months of the year, critters including mice, rats, squirrels, bats, birds and snakes will seek shelter in a warm place. A covered HVAC unit is an easy target for these vermin. If critters get into the unit, they could damage its wiring, coil or other components, leading to the need for a costly repair. Animal droppings and nesting material release acids when they decompose, and those acids could corrode the outdoor unit’s metal. It’s better to leave the unit uncovered so that it doesn’t appeal to vermin.

HVAC Damage May Be Caused By Improper Cover Use 

Water on the condenser coil of a heat pump or air conditioner could make the coil freeze. Covering the unit could trap moisture there, resulting in a broken coil. A long cover could cause water to drip into the unit, which will also lead to problems. Some air conditioning manufacturers have specific accessories made for placing on top of the outdoor unit during the colder months of the year. Using anything else might void your warranty.

When Covering The Outdoor Unit Is Acceptable 

Whether you have a heat pump or an air conditioner, there is one time of the year when it may be advisable to temporarily place a short cover on the unit. This cover should be made of natural fabric, such as burlap or wool. The time of the year to do this is in the autumn when leaves, acorns and other debris could fall inside of the housing. This debris can damage the fan and coat the coil. Once the leaves and tree seeds have finished falling, remove the cover. Leave the outdoor unit uncovered for the rest of autumn and throughout the winter months of the year. Keep in mind that you should only put a cover on the outdoor unit if it won’t be in use. If you’ll need the heating function of your heat pump, don’t cover its outdoor unit. Doing so will hinder the heat pump’s ability to absorb energy from the outdoor air, and its coil could freeze.

True Heating & Cooling is the trusted provider of heating and cooling maintenance in Boulder and the surrounding area. You can also turn to us for cost-effective heating and air conditioning repair, replacement and installation services. Our indoor air quality solutions, carbon monoxide detectors and comfort control systems are designed with your safety, comfort and well-being in mind. To learn more about how to take care of your outdoor HVAC unit during the colder months of the year, get in touch with us at True Heating & Cooling today.