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Why is My Portable Air Conditioner Not Cooling?


Running your portable AC during the hot summer months can be very helpful in cooling you down. However, if it starts blowing hot air instead of cold air, it can become quite frustrating. 

There can be a few reasons why your portable AC unit isn’t producing cool air. Read on to learn more about what factors can affect your portable air conditioning unit and what steps you can take to resolve the issue.

Why Is My Portable AC Not Blowing Cold Air?

It can be very frustrating and alarming when your portable AC unit isn’t producing cold air. This issue can lead to multiple problems such as higher electricity bills, increased humidity in your home, or even health concerns due to extreme temperatures. 

Addressing the issue of your AC promptly can help you avoid those issues, as well as prevent further breakdown of your unit. If this issue isn’t solved right away, it may lead to costly repairs or you may even need to replace your whole AC instead. We’ve listed out some factors as to why your AC is not blowing cold air – have a look:

Insufficient Power Supply

A portable AC requires a certain amount of electrical power to function properly. If there isn’t enough power supply, the unit will struggle to operate and may not cool effectively. 

The compressor may suffer as well. The portable AC compressor is responsible for compressing the refrigerant in the AC system, necessary for circulating and blowing cold air in the room. If the compressor doesn’t operate properly, the refrigerant will not be properly compressed and the AC system will not be able to cool the air effectively, resulting in the unit blowing out warm or room-temperature air. 

Check the circuit breaker built into the AC’s plug as well the circuit breaker in your electrical panel. One of them could have tripped and caused the unit to malfunction.

Clogged Air Filters

The air filter is responsible for trapping dust, dirt particles, and other debris to keep your air clean. However, if there’s a buildup of debris, the air filter can get clogged and your AC can malfunction, leading to insufficient cooling performance.

A clogged filter can also interrupt the airflow, meaning that the fan may run when the unit is turned on but there may be no free cool airflow in the room. The interrupted airflow can cause the AC to stop cooling the room effectively. 

Furthermore, a dirty air filter can make an AC overheat and damage the unit’s components, resulting in a reduced lifespan. Clogged filters can make the AC work harder in circulating air through the unit and make it generate excess heat.

Refrigerant Leaks

The refrigerant is the substance that flows through the cooling system to absorb and dispense heat from the cooling chamber. It runs through the compressor and condenser and is converted from liquid to gas and back to liquid.

When your AC has a refrigerant leak, it can result in reduced cooling power. The unit will have to work harder in order to cool the room and use up more energy than usual, resulting in a higher electricity bill.

Blocked Airflow

If your AC is producing cold air but not cooling the room, it can be due to a lack of adequate airflow. A blocked airflow can happen due to a variety of reasons such as a dirty filter, inappropriately positioned vent hose, frozen evaporator coils, or something as simple as not having enough space around the AC. 

Any portable AC unit should have its exhaust hose properly installed. Any small bends can block the airflow, leading to a reduced cooling capacity. It’s important to make sure that the hose is properly positioned as much as possible to allow maximum airflow from the unit.

Leaky Exhaust Hose

As the name implies, the exhaust hose or vent hose of your AC is responsible for releasing the hot air to the outside of your home. If the exhaust hose is leaking hot air or is not blowing air outside, then the heat that your AC is removing is going right back into the room.

This can happen if the vent hose is bent at weird angles or misaligned. Hot air coming from the hose can also occur if there are obstructions such as leaves or debris.

Room Not Sealed Properly

If a space is improperly sealed, meaning not all doors and windows are closed properly, the AC can become overwhelmed. Air conditioners are designed to cool the air to a certain temperature range and when there’s a leak or the ambient temperature in the room is too high, they may not have enough power to cool the space.

Incorrect Unit Size

When shopping for a portable air conditioner, it’s important to check its specifications, particularly the cooling capacity or power potential. The cooling capacity of portable AC units is measured using British Thermal Units or BTU ratings.

One BTU is the amount of energy required to increase or decrease the temperature of a pound of water by 1 degree Fahrenheit. On average, a unit with a 12,000 BTU rating is enough to cool a 400 to 500-square-foot room. 

If your air conditioner has too many BTUs for the size of your room, the unit can cycle off too rapidly. On the other hand, if your unit lacks sufficient BTUs, it won’t have the capacity to impact the ambient temperature.

Faulty Temperature Sensor

A faulty temperature sensor can cause an AC unit to malfunction. A portable AC works by reaching the desired temperature set by the user. Once set, the unit will turn its compressor on and off to regulate the room temperature as required. If the sensor is not reading the temperature correctly, the portable unit may not blow cold air or its compressor can also shut off unexpectedly, failing to cool the area. 

Dirty Evaporator Coil

The evaporator coil is responsible for absorbing the heat in the room and changing it into vapor, allowing the room to cool. When the evaporator coil gets dirty, there can be a decrease in the effectivity of the heat transfer between the room air and refrigerant, therefore impeding the air conditioner’s cooling functionality. 

Frost can also form in the evaporator coils and this can lead to an obstructed airflow, which in turn can prevent the portable AC from blowing cold air. Moreover, frozen evaporator coils can also cause a host of other issues to your portable AC. 

Faulty Blower Fan

If there is little to no airflow coming out of the portable air conditioner, there may be an issue with the blower fan. The fan motor belt may be loose or it could have also slipped. It could also be that the fan speed is not set high enough.

There can also be dust piled up on the fan blades of the AC. Dust and dirt can weigh down the fan blade, making it tougher for the fan to spin and blow cool air.

Full Condensate Tank

Aside from cooling a room, air conditioner units also remove moisture from the air. Moisture from the cooled air turns into water, which is then collected in a condensate tank inside the unit. Some portable ACs have a drain line that drains the condensate directly out of the unit. 

Most of the time, this isn’t an issue, but there can be cases where the condensate will accumulate and fill up the tank. Sometimes, the condensate tank can also fill up if the line is clogged and not draining properly. It can make the air conditioner malfunction and block cool air from flowing smoothly.

How to Fix Portable Air Conditioners That Are Blowing Hot Air

It can be distressing to have a portable air conditioner that doesn’t have any cold air flowing or isn’t cooling the room quickly. Worry not, for there is still hope as there are troubleshooting steps that you can do to solve the issues of your portable AC. 

One of the first things that you can do is to check the mode setting your portable air conditioner is set to. Most air conditioners have several modes including Cool Mode, Fan Mode, Auto Mode, Eco Mode, and so on. Sometimes, it can be simply a case of your portable air conditioner being set to Fan or Dry Mode. If that is the case, simply switch it to Cool Mode to feel the cold air.

Check the temperature setting of your air conditioner as well. Ensure that the unit is set to a temp value that is low enough to enable it to cool the space. Your AC can only cool sufficiently if the set temp is lower than the ambient temperatures. 

Inspect the AC filters as well for any choke points or debris stuck inside. If you don’t clean your air filter regularly, you can run into a host of issues once the dust builds up in it. A simple solution of warm water with mild detergent can clean the build-up in the filter. Make sure to let it completely dry before installing it back.

If your air conditioner is blowing cold air but not cooling the room, check your unit’s hose and make sure it’s vented outside properly. Any weird angle or small bends can let the heat slip back into the room. Check the position of your unit as well and ensure that there’s adequate space around it and it’s not obstructed by anything. 

You should also check if all your doors and windows are closed. Even the smallest gaps can let the cool air escape from the room. You can consider insulating your windows with curtains or shades as well to reduce the direct sunlight streaming into the room which increases the heat load in your space. 

Furthermore, to prevent your portable air conditioner from breaking down multiple times, have it properly checked by an HVAC professional periodically. Getting your unit looked over and maintained by an HVAC technician can help you avoid issues in the long run and best of all, expand its lifespan.

Final Thoughts

A portable air conditioner that is not cooling a room effectively can be aggravating, especially if you can’t pinpoint the cause of the issue. It can be anything from an unsealed room to clogged air filters to a bent hose and the like. Make sure to thoroughly examine your unit and once you find out the cause of your problem, take the appropriate action to solve it.

If you’re unsure of what to do, you can always refer to your owner’s manual or better yet, contact an HVAC repair professional so that they can properly assess the problem and offer solutions. 

JP Reyes

JP has been in the aircon industry for almost as long as he has been alive. As a child JP would help his tatay fix aircon units at their junk shop in Cavite. After graduating UP in the early 2000's, JP then started his own Aircon servicing business and within 5 years had 10 shops in 8 different cities. Fast forward to today and JP brings all his experience and expertise online to give readers trustworthy advice and reviews about Air-conditioning buying, servicing, cleaning and repair in the Philippines.

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