Air conditioner compressor condenser unit overgrown, damaged, out of commission, without a cover (C) Daniel Friedman Air Conditioning / Heat Pump Covers
Should you cover your outdoor unit?

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Air conditioner protective-cover usage:

Questions & answers about whether or not you should cover your air conditioner or heat pump or window unit to protect it from snow, leaves, rain, debris. What damage can occur if you run the air conditioner with the winter-cover still in place?

This article series discusses the outdoor components of air conditioners and heat pumps: how the air conditioning compressor-condenser unit works; the detection of defects in air conditioning compressor and condensing units, including evaluation of air conditioner compressor noises, hard starting, lost cooling capacity, and detection of a burned out compressor or A/C compressors at or near end of their life.

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Air Conditioning Compressor / Condenser Covers or Window A/C unit Covers

Enclosure around through wall air conditioner (C) Daniel FriedmanOn 2017-05-06 by Mark: I ran our air conditioner with the cover on

my air conditioner was run accidently with the cover on. What kind of problem will that create? and how best to diagnose?

On 2017-06-06 by (mod) re: ran A/C with cover on - what damage might be caused


The concerns about running an A/C unit with the cover on would be around problems with overheating:

Snow covered  compressor condenser unit Glens Falls NY (C) Daniel FriedmanI

I have searched for but could not find air conditioner winter-cover instructions that addressed the risks of turning the system on before removing the cover.

Our photo (above-left) shows a snow-covered compressor/condenser unit un-covered except for by snow, in Glens Falls, NY. This unit is placed too close to the building wall - blocking air flow through the unit.

This installation may also void the manufacturer's warranty as it is not properly installed. These effects of blocking air flow to part of a compressor/condenser unit are likely to be similar to those of running an A/C compressor unit while it is covered-over. Our photo below shows a typical after-market "winterizing" or "protection" cover for an air conditioner compressor/condenser unit.

Round air conditioner cover at

When you run an air conditioner or heat pump with a cover over it, the results of blocked air flow through the compressor/condenser unit reduce its efficiency and effectiveness and reduce its life as overheating of motors or other components may occur: depending on several variables including how long the unit was run and the outdoor temperature.

More about the effects of restricted air flow across the compressor/condenser unit of your air conditioner is at CLEARANCE DISTANCE, HVAC

My OPINION is that if the unit is operating normally now and you don't see nor smell evidence of burned electrical components, I wouldn't invest in further diagnostics.

If your A/C unit is not running it may be due to a motor overheating and cutting off on thermal overload. Some electric motors include a reset button but most on air conditioners do not. In those motors leaving the system turned off for 10 minutes or possibly longer (an hour or more) to allow the motor to cool should cause it to automatically re-set itself.


If the system is not running properly and a thermal reset or circuit breaker reset has not corrected the problem you should call your HVACR service company for repair help.

Permanent cover over an air conditioner compressor condenser at Hotel Palomar San Miguel de Allende Guanajuato (C) Daniel Friedman

Watch out: At least some HVAC technicians describe air conditioner covers as unnecessary, possibly harmful, and something that makes still more money for the repair guys who have to be called in later.

In addition a permanent "cosmetic" cover over the outdoor compressor/condenser unit such as the steel strapping wrapping the unit we show here is likely to interfere with the unit's effective operation and to shorten the life of its compressor motor and fan motor because of the significant reduction in air flow through the unit.

This A/C cover in intalled over a rooftop compressor/condenser unit at the Hotel Palomar in San Miguel de Allende.

While a "cover" for a window or free-standing air conditioner outdoor unit can protect a unit from debris when it is not in use, a cover that traps moisture inside the unit can cause far more damage than good by encouraging corrosion of metal and electrical components.

In some locations a cover on an A/C unit may also invite a mold (see SPLIT SYSTEM AC MOLD CONTAMINATION REMOVAL), mouse, rat, or squirrel invasion - we've found an occasional mouse inside of HVAC equipment. Those critter in turn may enjoy chewing on components and wires.

If you are going to use an air conditioner cover be sure it's a "breathable" cover not simply a plastic wrap. Or just cover the unit's top to keep leaves and debris out.

Residential HVAC equipment that is located outdoors (a window air conditioner or a compressor/condenser unit for central air or a split system) is designed to be exposed to the weather without damage, but in my view you should either protect the unit with a breathable top cover to keep leaves and debris out (if those are nearby) or you should check for and clean debris out of and away from the system before it is returned to service.

When should you cover an air conditioner? Our review of online comments by HVAC service companies found a few who suggest that you might want to protect the outdoor unit temporarily from unusual weather such as a severe hail or thunderstorm or blizzard that may form ice inside and damage the compressor unit components.


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AIR CONDITIONER COVER USE at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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