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Why is My Portable Air Conditioner Not Cooling (And How to Fix It)


An unfortunate occurrence that requires prompt attention is when your AC unit breaks down in the summer. Most portable air conditioners encounter issues with hot air coming from the exhaust. Meanwhile, some units are producing cool air but don’t have enough cooling power.

Issues like a clogged filter, an incorrect temperature setting, fan hiccups, and the like, may be to blame for portable air conditioners not blowing cold air. In this article, we will delve into the reason why portable air conditioners are not cooling.

Why is My Portable Air Conditioner Blowing Hot Air?

There might be several reasons your portable air conditioner is leaking hot air instead of cool air. It’s such a nuisance when this happens, especially during hot steamy weather. Here are the potential reasons why your portable AC unit is not maintaining cooled air. 

The Weather is Too Hot

Your portable air conditioner functions through evaporative technology. It uses a specific heat load to cool down a certain area. Water doesn’t evaporate fast, hence, it can absorb heat for a decent amount of time. However, the capacity of portable ACs to maintain cold air inside a room will not work in high-humidity places.

Cooling the room can frequently be attributed to how the unit was installed or placed in your home, depending on the room size.

There is a Blockage in the Air Intake

Sometimes, the reason your portable AC unit is not blowing cold air is that there is a blockage in the airflow. The main feature of a portable AC is its easy mobility. However,  portable ACs use the same refrigeration cycle as most air conditioners, so their mobility is somehow restricted.

After absorbing heat from the condenser coil, air must be drawn in from the surrounding area and delivered to the portable unit. Then, the exhaust hose is used to release warm air outside.

A portable AC will stop cooling the refrigerant in the evaporator coil to the condenser coils if there is no adequate airflow. As a result, both the portable AC’s efficiency and cooling effectiveness will be impacted.

Dirty Air Filter

If you’re not checking up on your portable AC, there is a huge tendency that it might underperform as time goes by. As such, air filters are the most vulnerable to damage, due to accumulated dust, moisture, and dirt, which may block cool air from producing maximum airflow.

Broken Thermostat or Temperature Sensor

A broken thermostat means that the AC will not detect temperature change and know when to turn it on or off. If this happens, hot air leaks instead of cool air, making the home warmer than intended as it turns on and off dramatically.

Frozen Evaporator Coil

When the airflow of the air conditioning system drops below a specific level, the refrigerant of the portable AC passing through the evaporator coil is unable to absorb enough heat. This means that a dirty evaporator coil won’t be able to exchange heat efficiently with air flowing through your AC unit. 

If your evaporator coils have ice, leave the AC turned off to allow the ice to melt before switching it on again. Note that leaving the evaporator coil to defrost by itself can take many hours. You may want to speed up the defrosting process by running the unit in fan mode.

Clogged Drainage Line

A portable air conditioner not blowing cold air can also indicate an issue with the drainage line. Although most portable units will have a tank or a condensate tank, some could also have a drainage pipe. If your line has a clog or is not draining properly, your AC unit could stop cooling.

Other Possible Issues

If you see error codes on a display, warning beeps, or if the fan blade doesn’t spin when the machine turns on, you’ll need to check the owner’s manual or call for an HVAC repair.

If your portable AC has a problem with its error code, check the code in the user manual and according to the explanation, decide if the issue can be easily troubleshot or if you need to call an HVAC tech.

How to Fix an Air Conditioner That is not Blowing Cold Air?

When your portable air conditioner stops blowing, it could mean that there are a few different problems. Here are some of the troubleshooting steps to do to make your portable AC work:

Check the Power Button and Mode Setting

The first thing you should do is check the settings of your portable air conditioner. Make sure the unit is set into cool mode before doing anything else. The temperature value of your portable air conditioner should be low enough to have a chilling effect in your room.

You can always check the temperature setting of your portable AC using your thermostat. It must be lower than the ambient temperature of your room because your portable air conditioner works via evaporative technology. 

As a result, setting a reverse cycle higher than room temperature instructs the device to heat while setting it lower causes the system to cool. Therefore, if your portable AC unit is not blowing cold air, it’s possible that you set the thermostat higher than the room temperature, instructing your cooling system to heat rather than cool.

Check the Exhaust Hose

Ensure the exhaust hose is securely connected to the unit and window bracket. You can do this by turning the hose end to lock it in place. 

Clean Your Air Filter

Clogged and dirty AC filters can drive up your bills by forcing your HVAC to work continuously by cooling or heating, and therefore harder to pull from the AC unit.

If the air filters are dirty, blow the dirt off with a vacuum cleaner attachment or wash them with warm water and a little detergent.  Regularly clean air filters to ensure the overall health of your AC unit. Take note that you should never wash air filters in a dishwasher or use hot water or harsh abrasives. Ensure the filters are completely dry before replacing them.

Turn Up Your Fan Speed

The fan may have stopped blowing hard, causing low airflow. This could occur if the fan speed is not set high enough. Make sure to check the fan itself along with the fan motor. First, switch the speeds of the fan from low to high in order to see if this makes a difference. If not, you can clean fan blades to ensure they are not obstructed by dust.

Check the Vent Hose

Check your unit’s vent hose and ensure it has been properly vented outside and not leaking or twisted. If the vent hose is not correctly vented, the heat the AC is removing could be slipping back into the room instantly!

Insulate the Room

If you get direct sunlight shining through a window, it can add 10% to the heat in a room. Insulate your windows with shades, curtains, or reflective film to keep the heat out. Close all open doors and windows as warm air may be creeping into your room, making it more difficult for the portable AC to cool it. 

Portable AC units are measured in terms of BTU ratings, which need to align with the size of the room you are trying to cool. If a unit has too many BTUs for a space, it will create an issue where the unit cycles off too rapidly. On the other hand, a unit lacking sufficient BTUs doesn’t have the power necessary to impact the ambient temperature.

Final Thoughts

If your portable air conditioner is not blowing enough cold air, then there are a few things that may be causing the problem. Keep in mind that if something is wrong with your AC unit, it does not mean that it is broken or needs to be replaced immediately. 

You should check the unit and make sure that nothing is blocking the way for the cold air to flow through. Also, ensure that the unit has enough space around it for proper operation.

If you are still encountering problems with your AC unit, you may want to contact an expert to fix the problem.

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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