5 Reasons You Should Never Lay Portable AC On Its Side

Josh Mitchell

Written By

Josh Mitchell

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Holly Curell

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As a fellow portable AC owner, I understand the flurry of questions that come with these nifty devices.

One question often pops up: "Can you lay a portable AC on its side?" It's a practical concern, especially when you're moving or storing it.

Having been in the same boat just recently, I dove deep into the dos and don'ts to ensure my AC stayed in tip-top shape.

Through my research, I've gathered crucial insights on this topic that I'm eager to share.

Let’s begin!

Key Takeaways

  • You should never lay your portable ACs on its side.
  • Laying portable AC on its side can damage its internal components such as the compressor and the AC coils, and also hinder the performance of the refrigerant.
  • When transporting and storing, make sure to keep the portable AC upright.

5 Reasons Not To Lay Your Portable AC On Its Side (Even When Storing)

Laying your portable AC on its side, even just for storage, is a no-go for several key reasons.

From potential oil leaks to internal damage, the risks are real.

Here, I'll break down why keeping your AC upright is more than just a recommendation—it's a necessity.

can you lay portable AC on its side

1. Compressor Can Get Damaged

Laying a portable AC unit on its side can lead to serious damage to the compressor, the heart of the unit.

The compressor, responsible for circulating refrigerant, relies on oil for smooth operation.

When the unit is not upright, the oil can migrate and prevent the compressor from functioning properly.[1]

I learned this the hard way when I moved to a new house one winter.

Despite securing my portable air conditioner and transporting it upright as the instructions advised, it accidentally got left on its side for more than 24 hours.

When I finally turned it on, it was clear something was wrong. The compressor struggled, and the unit didn't cool efficiently.

TL;DR: For the safety of the compressor, do not lay the portable AC on its side.

2. Internal Fixtures and AC Cooling Coils Can Get Damaged

When an air conditioner is laid on its side, internal fixtures, particularly the cooling coils, are at risk of damage.

These coils, vital for the air conditioner’s cooling process, can become misaligned or bent.

In one instance, after rearranging my room, my AC unit accidentally tipped against the wall.

Though it seemed fine initially, I later realized the cooling coils were damaged, impairing the unit's efficiency.

It's a reminder that even a temporary change in position can have lasting consequences.

TL;DR: AC coils can get pressed if it is laid on its side. This can hinder the cooling performance.

3. AC Refrigerant Lose Ability to Cool

Storing a portable AC on its side for more than a day can cause the refrigerant, crucial for cooling, to lose effectiveness.

The refrigerant needs to flow correctly through the coils, and this flow can be disrupted when the unit is not upright.

A neighbor accidentally once stored his AC sideways over the winter, and when summer came, it just couldn't cool as before.

The refrigerant seemed to have lost its ability to cool efficiently.

Upon researching what happened, I found out that improper positioning can lead to poor circulation, reducing the unit’s cooling capacity.[2]

That’s why it's best to always store and rest your AC in an upright position to maintain its cooling efficiency.

TL;DR: Refrigerant is designed to flow properly when the AC is laid in an upright position. In any other position, it looses its ability to cool.

4. Drain Water Will Spill Out of the AC

Apart from damaging an air conditioner’s internal parts, laying it on its side can lead to an unexpected mess, as drain water trapped inside may escape.

This water, meant to be drained out properly, can leak into internal components if the unit is not upright.

It's crucial to keep these units standing upright to avoid such spills and ensure they stay clean and functional.

TL;DR: Laying the unit on its side is particularly dangerous if it still has drain water inside.

5. Jams Filter Drier

Another reason why you shouldn’t lay down portable AC units is that it can cause serious issues with the filter drier, a component critical for absorbing moisture in the system.

Portable air conditioners left unplugged and on their side will result in a jammed filter drier over time.

It's a matter that often goes unnoticed but can severely impair functionality.

Ensuring the AC is upright helps avoid such jams, maintaining the efficiency of the filter drier and the overall health of the unit.

TL;DR: Similar to many internal components, the filter drier is yet another component that can get critically damaged. 

Can You Lay Portable AC On Its Side When Transporting?

No, it’s not recommended for an air conditioner to lay on its side when being transported.

Doing so risks damaging internal components, even during short transports.

So, only transport a portable air conditioner in an upright position, and keep it secure so it won’t turn sideways or upside down.

How Long Can You Lay It On Its Side When Transporting?

Ideally, you should avoid leaving a portable AC on its side when transporting. If necessary, do it for as short a time as possible and stand it upright quickly.

It's important to minimize the time spent sideways to prevent internal damage or coolant displacement.

How Long to Keep It Upright If It Has Been Laid On Its Side?

If your portable AC has been laid on its side, leave it upright for at least 24 hours.

You need to wait this long for the internal fluids, particularly the oil, to settle back into place, ensuring the unit functions correctly when you turn it on.

Important Note

There is no guarantee that your portable AC will work properly even if it has been let standing upright for 24 hours. Hence, avoid laying it on its side in the first place.

Safety Tips To Follow When Transporting Portable AC

  • Before proceeding with the transport, ensure that the AC is securely standing on its feet to maintain internal component alignment.
  • Place the AC securely on a flat surface in your vehicle to avoid it from turning or tipping over during transport.
  • When driving, take care to avoid sharp turns or sudden stops that could cause the AC to shift or fall.
  • If possible, use straps or supports to keep the device firmly in place during the journey.

TL;DR: You should never lay portable ACs on its side when transporting but if you absolutely have to, do it for a very short while. If its been laid on its side, wait for 24 hours for the fluids to settle before turning it on.


What Is The Correct Position Of A Portable Air Conditioner?

The correct position for a portable air conditioner is upright, near a window opening, for proper venting. This position ensures optimal performance and prevents damage to the unit.

Does A Portable Air Conditioner Have to Sit On The Floor?

Yes, a portable air conditioner should sit on the floor for stability and proper function. This position ensures portable ACs fit well in the space and operate efficiently.

Can You Put A Portable Air Conditioner In A Horizontal Window?

Yes, you can put a portable air conditioner in a horizontal window as long as it is made for window installation.

Many models come with adjustable window kits that fit various window orientations, providing the answers to diverse installation needs.


  1. https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=3331&context=iracc
  2. https://www.sciencedirect.com/topics/engineering/refrigerant-leakage 
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Josh Mitchell


Josh Mitchell
My name is Josh and I am obsessed with home appliances. From portable AC units to heaters and air purifiers, I enjoy testing, learning and using these devices to improve the air quality inside my family home.

My Favorite Home Appliance?

Midea U Shaped Window Air Conditioner

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