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Portable Air Conditioner Not Very Cold? 5 Reasons Why

It’s the hottest time of the year and your portable air conditioner is cooling yes, but the cool air never seems to be enough for the room. Your spot cooler is the only one you are relying on and you want this issue resolved quickly so you can enjoy some cool. So, why is your portable air conditioner not as cold anymore?

A portable air conditioner might not be very cold if it is too small for the size of the room, the room is poorly insulated, the room has a high humidity level, the cooling unit is dirty and clogged, or the portable AC is too old to keep cooling.  

If any of these issues is the case, you could save yourself from melting with the summer heat by samsung air condition troubleshooting or seeking the services of an expert HVAC technician for the complex ones. You can decide which of the two options applies by reading the details on the 5 reasons your portable air conditioner is not very cold anymore.

1. Your portable AC is too small for your room.

The size and BTU rating of a portable AC are determine the amount of cooling that they can do per square foot of space.

As such, before buying a portable air conditioner, you should know the size of the room where you intend to use the portable AC and purchase a cooling unit with the right BTU rating for your room size. 

You can consult an HVAC expert for advice on how big your portable AC should be. Alternatively, you can measure your room size in square feet (length x width) then use the ENERGY STAR cooling space vs BTUs table to find out how big (in BTUs per hour) your portable AC should be.

For example, if your room is 40ft by 45ft (1,800sq.ft), then you need a portable AC with 30,000 BTUs per hour. If you are using one with only 14,000 BTUs per hour, then you’ll certainly be feeling your portable air conditioner is not very cold.

Your room has poor insulation.

Air conditioners release cold air into the room and vent hot air outside of the home through a hose. Removing hot air from the room creates an imbalance in air pressure, which causes hot air from the adjacent ambient space (other rooms in the house) to be pulled in the room. 

If the room you are trying to cool is not well insulated and some unintended hot air entry points from the outside, other adjacent rooms, other appliances producing warm air, or even from leaks on the vent hose, then you’ll feel like the portable air conditioner is not cooling the room.

To offset this imbalance between the cool air produced by your portable AC and the hot air pulled into the room from adjacent spaces, you need to ensure that the room is well insulated and has no hot air leaks. Here’s how you can do this:

  • Close any open doors or windows that are letting in warm air into the room.
  • Replace single-pane windows with double-pane windows to enhance insulation.
  • Seal any spaces on your doors that are letting in warm air. You can use weather strips like a door snake on smaller air inlets or a draft stopper under-door seal on doors with extra-large gaps.
  • Close any leaks on the window venting and seal off air leaks on your windows using double-sided foam tape. See how to do that here.
  • Use curtains or blinds to block direct sunlight from getting into the room.
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The room you are cooling has a high humidity level.

Air conditioners cool space by removing heat and moisture from the air. As such, high humidity levels can make cooling your room a nightmare because your portable AC has to work extra hard. 

If your portable AC is not up to the task of cooling an extremely humid room, it will not deliver the kind of cooling that makes you feel comfortable, which is why you’ll also feel like your portable AC is not very cold.

According to Energy Star, the optimum humidity levels in a building should be between 30 and 50 percent. Humidity levels above this limit will not just make cooling more difficult, but they will also promote bacteria growth and make you feel uncomfortable.

To resolve the humidity issue and the problem with a portable air conditioner that is not as cold anymore, run the portable AC in the DRY mode for 1-2 hours. This will create a balance in the humidity levels and increase the portable AC’s efficiency in circulating cooled air.

Note that, even though a portable AC that is running in the DRY mode feels like it’s producing cooled air, the apparent cool air is actually dehumidified air and your AC is not actively cooling the room.

Your portable AC has a dirty interior.

A dirty portable AC is an inefficient cooling unit. This is why a greater part of the routine maintenance of a cooling unit is about removing dirt and maintaining the system in a clean condition.

Dirty air filters, dirty evaporator coils, a dirty fan blower, and a dirty portable AC outer casing are all possible causes of poor airflow, overheating, and other AC problems.

If your portable AC is receiving little air into the cooling chamber due to clogged air filters, for example, the output cooled air will just be as limited and your portable AC will not be very cold.

It’s important to ensure that your portable AC stays always clean by doing the following:

  • Check the air filters for dirt and blockage every month.
  • Clean or change air filters (as the case requires) every 3 months.
  • Clean the fins of the evaporator coils at least once every year. 
  • Have an expert HVAC technician clean the fan blower of your portable AC during the routine maintenance of your portable AC. The fan blower requires disassembling and is best handled by an HVAC pro.
  • Dust the outer casing or your portable AC daily during the cooling season. Keeping the unit clean on the outside helps keep the inside clean as well.
  • Ensure the room you are cooling is clean always as any dirt particles will be easily sucked into the unit with the air and, consequently, clog the air filters. 

Your portable AC is too old.

A portable AC can last for around 10 years or 15 years for strong models with good care and consistent maintenance.

If after this period your portable air conditioner is not as cold anymore, you should resign yourself to the fact that it’s time to put in a good bit of your hard-earned bucks into buying a new cooling unit.

A poorly maintained portable AC will have broken parts and frequent repairs. In this case, the spot cooler may need replacement even before the average 10 years lifespan.

Ensure you get an up-to-the-minute model when replacing an old portable air conditioner; one that will best meet your cooling needs. 

We can help you get the advice of a reliable HVAC professional on what the best models of portable air conditioners in the market are. Simply fill the form at the bottom of this article and we’ll connect you with the best portable AC repair pro. 


  • Jake Alexander

    Jake is a freelance writer from Pennsylvania who enjoys writing about science and sports. When he's not writing for Temperature Master, he can be found watching the NFL or playing basketball with his friends.

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