Ought to You Cowl Your AC Unit within the Winter? Skilled Steering

Must you cowl your AC unit within the winter? Normally not, in the event you imply wrapping an out of doors central AC condenser in a full cowl. Lennox says it doesn’t suggest protecting an out of doors unit “except you’ve got a compelling cause,” and notes that trendy air conditioners are designed to dwell and function outdoor. A full cowl, particularly plastic, can lure moisture and provides mice a spot to shelter. A warmth pump that runs in winter should keep unobstructed, and no outside unit ought to ever run whereas coated.

There are a couple of circumstances the place defending the highest of an idle AC unit is smart. Here’s what the producers and public power packages say, the place the recommendation differs, and what to do as a substitute.

The brief reply from producers

Lennox usually advises towards full winter covers, saying that protecting a unit fully, “particularly with a plastic or vinyl materials,” can do extra hurt than good, and that moisture captured underneath a canopy can result in rust and corrosion. Amana addresses a narrower level: it says by no means to function an out of doors unit whereas it’s coated, as a result of restricted airflow could cause system injury.

That is producer steerage, so it displays what these firms say about their very own gear. Your unit could have completely different directions, so your proprietor’s handbook is the tiebreaker.

Why a full cowl can backfire

Warmth pumps and mini-splits: don’t cowl them

A warmth pump is each your air conditioner and your heater, so its outside unit works all winter. Lennox is direct about it: warmth pumps that run year-round ought to by no means be coated. Our studying: the identical logic applies to a mini-split that heats, however test your handbook.

The NYSERDA heat pump maintenance fact sheet tells house owners to maintain the outside unit away from obstructions like leaves, particles, snow, ice and water runoff from the roof, and to trim vegetation so airflow will not be restricted. Efficiency Maine heat pump tips says to clear snow drifts away from outside items, hold shrubs away and take away caught leaves, and notes that warmth pumps defrost robotically.

A storage cowl will not be the identical as an overhead shelter. The NYSERDA sheet says a rain and snow shelter may also help cut back the work wanted to maintain the unit clear. A shelter or rain cap could make sense when it retains the producer’s required clearances and doesn’t block consumption air, exhaust air or service entry. By no means drape a canopy over an working warmth pump or set a lid immediately on it. For roof runoff, Efficiency Maine suggests a rain cowl or diverter on the roof to direct falling water away, and says that water falling onto the unit can freeze on the fan.

When protecting the highest could make sense

Lennox doesn’t say a canopy is all the time fallacious. It says a canopy could assist if you’d like safety from falling particles or leaves, and suggests securing a chunk of plywood on high with out proscribing airflow. InspectApedia, an unbiased reference that partly displays its writer’s opinion, says short-term safety from uncommon climate, equivalent to hail or a blizzard, could also be cheap for an AC-only unit. A plywood lid is safety from leaves and light-weight particles, not from a big falling department.

Our sensible tip: in case your producer permits a canopy for an AC-only condenser that’s shut down for winter, select a model-compatible high cowl or a securely fitted inflexible lid. Depart the perimeters open, make certain it can not blow off or block airflow, and keep away from wrapping the gear tightly. If the producer presents an adjunct on your mannequin, verify whether or not it’s meant for seasonal shutdown or to be used throughout operation, and set up it precisely as instructed.

What to do as a substitute of protecting

1. Take away free particles from across the unit. Effectivity Maine warmth pump ideas says to maintain shrubs away and take away leaves that get caught within the unit, and to keep away from bending the fins. Observe your handbook, shut the gear off as directed earlier than cleansing, don’t attain by the fan guard, and don’t take away panels.
2. Preserve branches and shrubs exterior the producer’s required clearances, together with the house above the unit.
3. Verify the unit after every snowfall. SaveEnergyNB says to maintain the outside unit away from snow and notes that buildup can starve the machine of air.
4. Redirect roof runoff so water doesn’t drip onto the unit.
5. Schedule skilled service on the interval advisable on your system. Our HVAC tune-up guide explains what a technician checks.

Snow and ice on the outside unit

A skinny layer of frost on a warmth pump in winter is regular. Carrier says a lightweight layer of frost, usually lower than 1/4 inch, ought to clear throughout the unit’s computerized defrost cycle, which generally lasts about 5 to 10 minutes. It says ice thicker than 1/4 inch, a stable coating, or ice that doesn’t clear throughout defrost will not be regular, and advises turning off the system and contacting a certified HVAC skilled. It additionally says by no means to chip ice from the coil. If meltwater is refreezing on the coil, Provider suggests discovering the supply, equivalent to a leaky gutter.

Window air conditioners

Window items are a special case. ENERGY STAR recommends eradicating a room air conditioner on the finish of the cooling season, if attainable, to reduce warmth loss, or utilizing an appropriately sized cowl throughout winter. Observe your mannequin’s directions for elimination, storage and protecting, and get assist lifting a heavy unit.

Should you do cowl it, take away the duvet earlier than turning the AC on

Amana says by no means to function an out of doors unit whereas it’s coated. Our sensible tip: set a calendar reminder for the primary heat week, and tie a brilliant ribbon to the duvet so it’s exhausting to overlook.

Incessantly requested questions

Associated studying

Sources

• Lennox, “Ought to I cowl my AC unit within the winter?” (April 2025)
• Amana, “Ought to I cowl my outside unit within the fall and winter?”
• NYSERDA warmth pump upkeep reality sheet (NYSERDA, State of New York)
• SaveEnergyNB, “Sustaining your warmth pump” (NB Energy, Authorities of Canada and Province of New Brunswick)
• Effectivity Maine warmth pump ideas, “Warmth Pump Person Ideas”
• Provider, “Warmth Pump Troubleshooting Information”
• ENERGY STAR, “Room Air Conditioners” (U.S. EPA and DOE)
• Effectivity Maine, “Making the Most of Your Warmth Pump”
• InspectApedia, condenser protecting cowl steerage (unbiased reference)