Can You Install Window AC Units Sideways?

Not all windows slide up and down. If you have a gliding window that moves horizontally, or if you have a narrow vertical window, you might be wondering, “Can you install window AC units sideways?” It’s a common question for homeowners dealing with older homes, as well as people in apartments. Flipping the unit around sounds like a quick solution, but turning a window air conditioner sideways can lead to serious problems. If the unit isn’t designed to be on its side, it’s never recommended to install it that way. Otherwise, you could be looking at AC compressor replacement. It’s also a likely way to shorten the unit’s lifespan.

Fortunately, you have alternative cooling solutions for narrow windows and gliding windows. With the right setup, you can protect your investment and keep your home comfortable during all of the hotter months.

Can You Put an AC Window Unit on Its Side?

Simply put, you should not install a window AC unit on its side. Standard window units are meant to work only in an upright position. That being said, there are units that are specially designed to work as vertical AC units or casement window air conditioners.

If you’re using the wrong model, though, tilting or turning the air conditioner on its side will change how the compressor oil and refrigerant move through the system. You need the compressor oil to stay in place. If it’s moving, that can lead to overheating, compressor damage, and failure to drain properly. Never turn a standard unit sideways.

Why Do People Want to Install Window Air Conditioners Sideways?

Many people ask, “Can you install window AC units sideways?” because their window AC won’t fit in a narrow opening. Older homes and even some apartments often have sliding windows or casement windows instead of traditional double-hung ones. The standard window units won’t fit in their normal installation pattern, so people often wonder if they can simply tilt the system on its side. But this is a problem.

Other people consider sideways installation to save space or avoid blocking natural light. The idea might seem practical at first, but it’s never recommended. Doing a sideways AC installation just puts you at risk for bad drainage, frozen coils, and loss of cooling efficiency. There are other units that are specifically meant to be on their side. Opt for those instead!

What Happens If You Install a Window AC Sideways?

Turning a window air conditioner sideways messes with how the internal components work. For example, the compressor oil pools in the wrong areas, and that prevents the compressor from getting the lubrication it needs. Over time, you’ll be looking at AC compressor damage and overheating.

What’s more, the drain holes inside the unit are meant for water to flow downward. When the unit is tilted or sideways, condensate can’t drain properly. Then you’ll be dealing with water leaks inside your home or rust within the system. This also affects the air flow and overall cooling performance. It’s just a mess for efficiency.

How Does Compressor Oil Work in Window Air Conditioners?

The compressor oil inside air conditioners keeps the motor running smoothly. It needs to remain at the bottom of the compressor to circulate with the refrigerant for cooling your home. When you install an AC unit on its side, that oil can flood the system’s tubing and prevent it from returning to the compressor. That leads to compressor damage and system failure.

Even if you later turn the unit upright, you’ll need to let it sit for several hours (ideally 24 hours) before powering it on, so the oil can settle back into place. That’s why window air conditioners should always remain upright. You don’t want to tilt them when you’re bringing them home from the store or during storage in the off-season. And you especially don’t want them on their side for installation.

Can You Install a Window AC Unit on a Side Sliding Window?

If you have a side sliding window, don’t be tempted to turn a standard window air conditioner sideways. Instead, look for a casement window air conditioner or vertical AC unit that’s designed for this type of setup. These models provide the same cooling power as traditional window units, but they’re shaped to fit tall, narrow openings. You need the right model to get proper air flow and condensate drainage.

Alternatively, a portable air conditioner can be a good fit for homes with sliding windows. These units vent through a small exhaust hose and a window panel. That way, you can eliminate the need for sideways AC installation entirely.

What Are the Best Alternatives to Installing Standard Window Units Sideways?

Instead of trying to install an AC unit on its side, consider one of the common alternative cooling solutions for narrow windows. First off, you have casement window air conditioners. These are designed for tall, narrow openings, like unique windows and windows that slide from right and left.

You can also go with a portable AC unit. These are easy to move and install without modifying your window frame. For a more permanent solution, there are ductless mini split systems. These are great for long-term energy efficiency and exact temperature control.

Where Can You Find Properly Sized Window Air Conditioners at Affordable Prices?

If your window AC won’t fit, don’t risk sideways AC installation. Instead, shop for narrow window AC models, casement window air conditioners, or portable air conditioners that fit your space in the right way. You can often find discounted or surplus units from HVAC suppliers that offer brand-name air conditioners at lower prices. Shop around for the best deals!