Portable Air Conditioner Compressor Keeps Shutting Off [11 Causes & Fixes]

I understand how frustrating it will be if your portable air conditioner compressor keeps shutting off on a scorching summer day. It will stop working when you are about to sit down to enjoy the bliss of cool air. 

The common causes of a portable AC compressor keeping shutting off include a dirty filter, low refrigerant level, frozen evaporator coil, and a full water tank, just to name a few.

I will detail all the causes and solutions/fixes below, so keep reading. Some will be easy things you can fix yourself, but others may mean calling an HVAC technician.

Ready? Let’s get started!

1. Dirty air filter 

dirty portable ac filter

Nine times out of ten, a dirty air filter is the culprit of a portable AC that keeps shutting off. 

As more contaminants are filtered out, the filter itself will become clogged, limiting airflow.

Because of the restricted airflow, the compressor will have to work harder to cool the room. The compressor will eventually overheat and shut down to prevent further damage.


Fortunately, the air filter is easy to clean. It only needs removing, washing, and then replacing. Note that you should ensure the filter is dry before returning it.

2. Low refrigerant level

The compressor in your portable AC requires refrigerant to work. By adding pressure to refrigerant vapor, it can boost the heat transfer process in the condenser coil later on. 

When the refrigerant level is low, it will lead to a high compression ratio and compressor overheating. 

In most cases, the refrigerant remains untouched in the coils and compressor. However, if there is a leak, the refrigerant level will gradually deplete.


You may want to give it a shot, but unfortunately, you should leave it to a certified HVAC professional. 

Because refrigerant is hazardous to the environment and our health, it is not permitted to repair or recharge your air conditioner on your own.

3. Filthy evaporator coil 

When the evaporator coil is dirty,  your air conditioner will freeze up and shut off automatically by making use of a sensor. Otherwise, the compressor will overheat and be damaged quickly.

As the ice thaws, you can see the machine is able to restart after a while. However, it will shut off again whenever the ice increases to a certain level.


Similar to cleaning the dehumidifier coil, you can clean it after disassembling the machine. There are some coil cleaners on the market that can dissolve the grime on the coil.

You can also use a soft brush or a vacuum cleaner to take away the dirt and dust on the surface.

4. Blocked inlet or hose

As mentioned above, restricted airflow can lead to a portable AC shutting off continuously. Except for the dirty components, problems in the venting process can also impede the airflow.

A piece of furniture, for example, may have obstructed the inlet, or the hose may be bent.


Fixing it is easy peasy!  Just take a look at the items around your portable AC and remove anything that may impact the airflow. Straighten the hose to make sure the hot air can go out smoothly.

5. Dirty condenser coil

Different from a dirty evaporator coil, a filthy condenser coil is not likely to cause your machine to freeze. However, due to the heat can’t be transferred outside, it will affect the cooling performance and result in short cycling. 


Likewise, you can use a soft brush or a specific cleaner to get rid of dirt and grime in the condenser coil. Nevertheless, it is hard to access. 

You can have a try if you have repair experience before. Otherwise, you should call for a technician.

6. Wrong temperature setting 

Portable air conditioners will shut off once the room temperature reaches the target temperature. 

As a result, if you set the temperature just slightly higher than the room temperature, it will complete its task and stop working immediately.


Adjusting the set temperature to at least 5 degrees below room temperature will ensure that your machine continues to work.

7. Your portable AC is too large for your room

It is important to run your portable AC in a room with the proper size. When the machine is oversized, it will cool the room down in a matter of a few minutes and turn off. 


There are two ways to cope with it. First, move your portable AC to a larger room, and you can stay in that space. Alternatively, purchase a new unit with a small capacity.

8. Condensate pan or tank is full 

You can drain your portable AC in various ways. If you have a full self-evaporative portable AC, you may not even require to drain water at all.

But when the weather is too humid, or you haven’t drained the water for a long time, the condensate pan will fill up with water. As a protection mechanism, some portable ACs will shut off in this circumstance.


You can remedy this problem by draining the unit. But if the problem continues to show up, you need to pinpoint the root cause of a drip pan full of water. For instance, the drain hose is clogged, or the condensate pump is faulty.

Then you can decide if hiring a pro is necessary.

9. Power supply issue

Any portable AC requires electricity to work. If your AC is not securely connected to the socket or the extension cord is not properly rated, it may be unable to receive a consistent and adequate power supply and will shut down.


Inspect all the connections and check the gauge of the extension cord. If they are fine, but the problem persists, you must contact a technician.

10. Loose wiring

If your machine has served you for years, chances are the wiring is loose. This will cause connection interruptions, making your machine shut off from time to time. 


Allow an HVAC technician to handle the job. They will troubleshoot any electrical issues that are causing your portable AC compressor to shut down.

11. Faulty compressor

This is the last thing you want to see because a new compressor can cost as much as a new unit. However, the compressor itself can fail at some point. 

When it is faulty, it is not able to deal with the workload and shuts off repeatedly. 


When the compressor malfunctions, it often means that your machine has run its life. Getting a new model is your best bet. If your machine is under warranty, you can contact the manufacturer to get a replacement.

Sum up

With any luck, this article has helped you to pinpoint why your portable AC compressor keeps shutting off.

Although reduced airflow is often the culprit, it can also be caused by wrong settings or a wrong-sized machine. 

You can prevent this from happening by committing to regular maintenance and cleaning. So, let’s check how dirty the air filter is first.

About The Author

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Liz Yang is the founder of Airsmartly. She has been working at home for a few years and realizes that the performance of the HVAC system plays such an important role in our life. She has tested dozens of products in person, like humidifiers, air purifiers, dehumidifiers, and ACs, and wants to share tips about using or troubleshooting these products with you. Her uncle is an HVAC expert with over 30 years of experience in the field, and often offers assistance when she is unsure how to handle a situation. He is also in charge of reviewing the articles on this site.

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