Window AC Not Blowing Cold Air (How To Make It Colder)

No one enjoys having a broken air conditioner. With the rising temperatures, a properly working AC unit is essential in many households, and there is nothing more frustrating than a window air conditioner that won’t blow cold air. This article aims to address the question, “why is my window air conditioner not blowing cold air?”

Why My Window AC Isn’t Blowing Cold Air? (Common Reasons Plus How To Fix It)

Your window AC not blowing cold air may be due to many reasons. Some are the type of reasons that you can fix on your own, while others may necessitate a trip to the professionals. Here below are the reasons and how to fix them.

Window AC Isn’t Blowing Cold Air

The AC Is in the Wrong Mode

A simple reason why your window AC is not pumping cold air could be that it is not in the suitable mode (cool mode). AC units are built to operate from different modes. These modes may depend on the particular model you are using, but most work in the same way. Most if not all window ACs operate between the following modes:

  • Cool mode
  • Dry mode
  • Fan mode
How To Fix It

Make sure your window AC unit is in cool mode. This mode removes heat from the room up to the required temperature in the AC thermostat. On reaching the desired temperature, it works to keep it at that level.

If it is still not working in the cool mode, you need to read on for additional sources of trouble.

The AC Filter Is Clogged or Dirty

The air filter needs cleaning now and then at regular intervals. If this is not done, the filter gets clogged, leading to the airflow being restricted, thus inhibiting the standard cooling capacity of the unit. It may also frost on the evaporator coils, further inhibiting air circulation.

Related Article How to Clean Window AC Filter

How To Fix It

Replacing the filter is the most advisable option. Secondly, you can clean the evaporator coils with warm water to unclog the filter area. Always check the filter at the back of the conditioner if it isn’t cooling as expected.

Undersized Window AC

Your window AC may be too small in comparison to your room. Different units remove different amounts of heat per hour or deliver cool air differently. The cooling power of window ACs is designated in BTUs (British Thermal Units).

How To Fix It

Check out the BTU ratings of your AC to ascertain its cooling power before you conclude that it is broken. It could just be that your AC is too small for the space you intend for it to cool. You can increase the size or buy a new unit with a higher BTU or buy a second unit to complement the first one.

Ensure that your cooling unit can handle the space you want to cool. This will prevent your unit from raising your power bill unnecessarily without the desired cooling effect besides ensuring that your room is adequately cooled. Remember not to make it too big as this will unnecessarily consume electricity besides cooling the house too fast and shutting off even before all the moisture has been removed. Maintain the perfect size of AC for your space; too small or too large is not recommended.

The Thermistor Is Broken

A thermistor is a gadget that monitors the room’s temperature to be cooled and sends signals to the compressor to either reduce or increase the cold air circulation. Once the desired temperature is attained, it communicates to the compressor to turn off the cold air. On the other hand, the thermistor signals the compressor to blast more cold air if it is hot. If the thermistor is broken, the cooling will not work either.

How To Fix It

Replace the damaged thermistor with a new one from your window AC manufacturers approved list. You can leave this with a professional since they know how to fix your dysfunctional thermistor. Before long, you will have your window AC up and running again and your house cool.

Compressor Failure

The compressor dumps out the heat and pumps cold air into your room. Therefore, the window AC won’t blow cold air without a properly functioning compressor. The AC blowing air that is warm in cool mode, for instance, indicates a failed compressor.

How To Fix It

If the compressor breaks down, it is best to buy a new window air conditioner. It is not worth it to replace the compressor for two distinct reasons. One is that by the time the compressor fails, it is clear that the unit itself is old. Secondly, compressors are expensive; hence it is more cost-effective to buy a new window AC than to replace a compressor.

My Window Air Conditioner Is Still Not Blowing Cold Air: Is It Time To Replace It?

Repairing a window air conditioner is a pretty costly affair compared to purchasing a new one. When confronted with a decision on whether to repair or replace, go with replacing; it makes more sense than repair. The older the unit, the less investment into repairs is justified as a rule of thumb.

The decision also depends on your circumstances, like your budget and plans. If you are soon moving to a different house, it would not be prudent to buy a new window AC.

The main advantage of replacing the AC over repairing one is that it is more cost-effective in the long run.

The disadvantage of replacing is that it may cost more in the short term.

Replacing Window AC Not Blowing Cold Air

How To Make A Window Conditioner Colder

Air conditioners work by exchanging air from outside the house with the air inside the house. If the air from outside is hot, you have to set the AC to cool the air inside. The same principle is used to make an air conditioner colder. This is how to make a window air conditioner cooler.

  1. Wash the filter by dipping it in soap water several times to get rid of grime. Rinse and allow to dry prior to putting it back in the housing.
  2. Dip the grill into the soapy water the same you did the filter. Use a brush to rub the grill to get rid of dirt and fuzz. When the grills are free-flowing, the air conditioner gets colder. The more air can get in through the grills, the more we can get the maximum cooling effect.
  3. Clean your evaporator coil. With time, debris will inevitably cover the surface of the evaporator coil, just behind the filter impeding the cooling process. Use a toothbrush or vacuum to clean the dust and clean the evaporator. Allow it to dry before putting it back on.
  4. Clean up the condenser. The AC sits outside and is exposed to a lot of foreign bodies. These bodies get attached to the condenser and inhibit the cooling process. To unclog the condenser, a toothbrush or vacuum will equally do.
  5. Straighten the fins. The coil fins are made of delicate metal, making them susceptible to hits by more prominent and heavier particles, rain, etc. Once they are bent, the airflow through your unit is significantly impeded. Remember, you need as much air as possible flowing through your AC system to make it colder. Get a fin comb to straighten the fins for more cooling efficiency.
  6. Wash the grates. The AC has external grates. If they get dirty, the unit cannot vent as required. To remove the debris, vacuuming will do.
  7. Locate the air conditioner on the side of the house with the most shade during the day. If the AC is facing the sun, it gets heated, and air coming through it will inevitably be hot, meaning that it will take more energy and effort to cool it down.

People Also Ask (FAQ)

Frequently asked questions on window air conditioner.

Can you add Freon to an air conditioner by the window?

Your AC should not require a refrigerant unless something is not working correctly. Apart from a refrigerant leak, refrigerant should never be added to an air conditioner and must be done by a professional.

Related Article Can You Recharge a Window AC?

Where is the thermostat located in an air conditioner by the window?

The thermostat is located behind the unit’s control panel.

Does resetting the window AC make the air colder?

No. Resetting the AC does not make it cooler. It does, however, restore it to default factory settings. What makes the air colder has been well explained above.

How long do window ACs normally last?

They last for between ten and twenty-five years instead of five and ten years for portable ACs. Location, maintenance, efficiency, and usage determine its life.


We have extensively discussed two main points: identifying why your window AC is not blowing cold air and, more importantly, the remedial measures you will take to address the breakdown.

I sincerely hope that you were able to identify and fix the matter that was preventing your window AC from cooling. If a component is broken, repair it unless the repair cost is prohibitive.

If it is not cost-effective to repair a part, consider purchasing a new window air conditioner. When purchasing an air conditioner, always remember to identify the right size for the space you intend to cover.

Josh Mitchell

Josh Mitchell

My name is Josh and I am obsessed with DIY and improving my family home. HVAC topics can be tricky for homeowners so I decided to share my knowledge on the subject. When I am not working on DIY projects, you can find me at the beach or my local coffee shop.