Can You Put An Air Conditioner Sideways In A Window? (Find Out Now!)

Dennis Howard
by Dennis Howard

Creativity is a great thing when approaching problems or tackling projects around your home. A little thinking outside the box can often result in unique and interesting ways to make your home stand out. Some homeowners wonder if installing a window air conditioner sideways to fit an unusual space or opening is possible.

Window air conditioning units should never be installed other than the way the manufacturer specifies in the installation guide. Installing a window AC unit on its side can lead to major problems, including the total failure of the AC unit. If you ignore the manufacturer’s directions, you will almost certainly void the warranty on your AC unit.

Most manufacturers include specific instructions on how and where a window air conditioning unit is installed. How these window air conditioning units operate makes it imperative that certain conditions be met during the installation. One of the most important is that the air conditioning unit is installed upright, flat, and level.

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Why Must my AC Unit be upright and level?

The need for a window air conditioning unit to be upright and level is directly related to how the air conditioner works. There are several reasons that the unit be installed upright and level for proper operation.

You Can Damage the Compressor

The compressor is the heart of your window air conditioning unit. Your air conditioner operates by compressing refrigerant gas and then letting it expand rapidly in a set of coils. This expanding gas cools and absorbs heat from the air blowing over the coils.

The compressor also contains lubricants that keep the compressor operating efficiently. If the compressor is tilted on its side, the lubricants can leak into the refrigerant lines and keep the refrigerant gases from moving through the coils. The compressor may also not get the lubrication it needs leading to a compressor failure.

Damaging the Compressor Mounts

The compressor itself is mounted on shock absorbers that reduce the vibration when the air conditioner is running. Tilting the air conditioner on its side hangs the compressor from these mounts instead of allowing the weight to rest on the mounts. The mounts are not designed to hold this weight in this position.

The mounts will quickly fail and, in some cases, allow the compressor to fall, which damages the refrigerant lines and possibly the electrical connections. For the most economical and efficient operations, the compressor must sit flat and level on the mounts.

Condensation Collection Problems

As warm, moist air from inside your home blows across the coils, the moisture in the air collects as condensate. Window air conditioning units have a collection pan beneath the coils to transfer the collected water outside your home.

If you sit your window air conditioner vertically, the condensate collection pan is no longer under the coils. The water that collects on the coils will drip into the air conditioner instead of being channeled outside. In some cases, the condensate may actually run into your home cause problems with mold and mildew

More Water Problems

The housing of your window air conditioner is designed to keep the outside weather outside. The top of the housing is intended to shed rainwater. The vents on the window air conditioner are placed on the sides to protect from rainwater incursion.

Turning your air conditioner on its side puts the side vents on top where rainwater and other debris can easily get inside. If the rainwater can get inside the air conditioner housing, it can also drip and run into your home.

Damage to the Housing and Air Conditioner Mounts

The mounting system with your window air conditioner unit was meant to sit in a specific way in the window or other opening. Window Air Conditioning units are heavy and must be properly supported by the structure of your home and the mount. Turning an air conditioner mount on its side induces stresses the air conditioner and mount wasn’t designed to handle.

These stresses can cause the mount to fail or allow the housing of the air conditioner to twist or warp. If the air conditioner mount doesn’t transfer the weight load properly to the structural members of your house, the weight can damage your home as well.

What are the Possible Solutions?

Fortunately, there are several viable solutions when a conventional air conditioner mount doesn’t work in your space. You might consider one of these options rather than try to mount a window air conditioning unit vertically.

Choose a Different Air Conditioning Unit

Manufacturers recognize that not everyone has the perfect window in which to place an air conditioner. Most manufacturers now offer different sizes and styles of air conditioning units adaptable to a wide range of window sizes and orientations.

Do a Little Creative Construction

If you live in a wood frame home, one option might be to install a larger window. This gives you several positive opportunities for your home.

  • You get the proper size opening for your window air conditioner, ensuring that it operates as it is designed.
  • Installing a new larger window often brings some energy savings. Installing a new high-efficiency window unit can reduce your heating and cooling bills.
  • A larger window can allow more light into your interior space giving your home a new feel and making the space more liveable.

This solution works well on wood frame structures with siding. However, on brick veneer homes, this solution requires much more work and usually hiring a bricklayer to make the opening. In addition, if you rent your home, you should never make structural alterations without your landlord’s consent.

Go Through the Wall Instead of the Window

Some homeowners opt to have an opening on an outside wall, especially for their window air conditioning unit. This offers a clean and effective solution. You can choose where to place the air conditioner for the best results. A through-wall installation also keeps your windows free of obstructions.

In most cases, we recommend hiring a contractor to create an opening for your air conditioner. Cutting or moving structural members on the frame of your house requires special knowledge. Under no circumstances do you want to violate the structural integrity of your home.

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A Correct Installation is the Only Way to Go

According to the manufacturer’s instructions, installing your window air conditioner is the only safe way to ensure that your AC unit functions properly. In any case, if your AC unit is new, the warranty requires that you install the unit according to the manufacturer’s directions. Don’t endanger your warranty and your investment by doing otherwise.

Dennis Howard
Dennis Howard

Dennis is a retired firefighter with an extensive background in construction, home improvement, and remodeling. He worked in the trades part-time while serving as an active firefighter. On his retirement, he started a remodeling and home repair business, which he ran for several years.

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