Why Is Your Portable Air Conditioner Not Cooling? Causes & Solutions

Many people prefer portable air conditioners because they are less expensive, easier to install, and can be moved around the house. However, like any AC, it can stop cooling at some point.

Why is your portable air conditioner not cooling or not cooling enough? Chances are you need to change the setting or clean the filter or coils. There are other causes, like the wrong size or the full water tank. 

I’ve summarized all the common causes and solutions in this post to ensure you can troubleshoot and fix this problem. Let’s get started!

Portable AC is on but not blowing cold air

When you feel your portable ac can’t make the room cool, you can place your hand on the top of the unit to test if it blows cold air. If your appliance is blowing warm or even hot air, it could be suffering from one of the problems listed below.

AC mode is wrong 

Portable air conditioners often come with three or four modes: dry, fan, cool, and auto. If you set it to a different mode than “cool,” it will not blow cold air. So, why not check out the control panel? It might solve your problem right away by changing a mode!

The set temperature is too high

If you haven’t modified the set temperature for a while, you may need to make some changes. The temperature you set may be higher than the ambient temperature, giving you the impression that it is blowing warm air.

Lowering the temperature is a natural solution. I recommend that you set it as low as possible in the beginning to see if it can begin to cool again.

Refrigerant leak

As you may know, a portable air conditioner uses refrigerant to absorb heat from the air. When the refrigerant level falls below a certain level, the reduced pressure in the coil absorbs excess heat and causes the evaporator coil to freeze.

When the coil freezes, it loses its ability to transfer heat out of the house, causing your portable air conditioner to begin blowing warm air.

You can try to use any of the methods here to check the refrigerant level and then make a call to a specialist to get it fixed. 

As a side note, recharging a portable ac could be expensive, making purchasing a new model a better option.

Dirty air filter

As I said, a frozen evaporator coil can make your portable unable to blow cold air. But many causes can lead to an ac to freeze up, not only the refrigerant leak. 

Your portable air conditioner has an air filter that traps dust, dirt, and other impurities in the air. It can become clogged over time and obstruct airflow. When the airflow decreases, the evaporator coil cannot be warmed up, affecting the performance of your air conditioner and eventually causing it to ice up and be unable to blow cold air.

Fortunately, this problem is extremely simple to resolve. You have the option of cleaning or replacing the air filter. When your portable air conditioner receives adequate airflow, it may back up and cool your room.

Filthy coils

The coils themselves can get dirty over time, which will also limit the airflow. Dust, grime, and mold can appear on them and impede heat transfer. Again, when the coil is frozen, your portable will stop cooling.

Cleaning the coils in a portable air conditioner may be more difficult than cleaning an air filter. To remove the debris, disassemble the device and use a brush or coil cleanser.

If you don’t know how to clean the portable air conditioner filter, you can hire a professional or contact the manufacturer, especially if it’s still under warranty.

Portable air conditioner is not cooling enough

If your portable AC unit isn’t having any of the issues listed above and is blowing cold air but not enough to keep your room cool, you should look into the causes listed in this section.

Note that a dirty filter and coil will prevent your portable ac from cooling enough and stop cooling when things worsen. But I don’t want to repeat it here.

Low fan speed

low fan speed

When your machine is in cool mode, you can check the fan speed setting. If it is set to a low level, you can try increasing it to see if the problem is alleviated.

The increased fan speed results in greater airflow and more cold air entering the room.

Windows and doors are open

If there is hot air seeping into your room constantly, the performance of your portable ac will decrease accordingly. 

For instance, you may forget to close the window in the morning because last night was cooler, and you decided to stop running your device and get some fresh air.

Check the window brackets and doors for leaks to keep the hot air outside from canceling out the cooling effect of your portable air conditioner.

Leaky exhaust hose

This is another common cause of a portable ac not cooling enough. If the exhaust hose is damaged, it can leak hot air out, which will go back into the room. In addition, something outside may block the hose, making the hot air can’t go outside smoothly. 

If the hose leaks, use a vacuum to remove any debris and replace it with a new hose.

It is also critical to check the hose for bends and kinks, which will prevent your portable air conditioner from cooling sufficiently.

Too close to the wall

Similar to a low fan speed, wrong placement can reduce the airflow, making it not able to produce enough cool air. 

If you put it too close to the wall, not enough airflow will get into the machine, affecting the performance naturally. 

Please double-check the placement for those who discover their portable air conditioner isn’t working properly after moving from another room. Place it in the center of your room to see if it can release more cold air.

High temperature outside

When the temperature in your area suddenly rises, your portable air conditioner must blow more cold air to keep you cool.

That is to say, your unit is in good working order, but the cold air it produces cannot compete with the hot air in your room. It does lower the temperature in the room, but not sufficiently to make you feel cool.

To maximize the cooling effect of your portable ac, close the curtain to block the sunlight and turn off any electronic devices that may generate heat.

Your portable is too small for your room

If you notice that your brand new portable air conditioner isn’t cooling enough, but the ambient room temperature isn’t very high, your machine is probably too small for your space. Chances are, your new gadget will work well in a smaller space.

Consider how many BTUs the model has when shopping for a portable air conditioner. The greater the BTU, the greater the area it can cover.

Room Size BTU
100 sq. ft.5000
200 sq. ft.6500
300 sq. ft.8000
300-500 sq. ft.10,000
500-700 sq. ft.12,000
700-1000 sq. ft.14,000
> 1000 sq. ft.18,000

Portable AC is not cooling because it can’t turn on

When you troubleshoot why your portable ac doesn’t cool the room, you may find that your device doesn’t make any noise, meaning that it doesn’t activate.

No power

Electricity is required for portable air conditioners to function. You should double-check that it is securely plugged in. It is also critical to ensure that the circuit breaker has not been tripped and that the outlet has power.

Full water tank

Most portable air conditioners include a float switch. When the condensate tank is full, it will automatically shut down. In humid climates, the condensate tank can become full, and the problem should be resolved after draining the water.

Wrap up

The purpose of this post is to teach you how to diagnose and repair a portable air conditioner that is not cooling. A faulty portable air conditioner may stop working, blow warm air, or provide insufficient cold air. All of these scenarios can cause your room to be less cool than you expect.

First, determine which scenario you encounter, and then examine the causes and solutions in this scenario, as illustrated above. Your portable air conditioner will begin to blow cold air again!

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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 a lot 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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