How to make window AC colder

Is your window air conditioner not blowing enough cold air?

Does it seem like no matter how low you put the thermostat, the temperature stays the same in the room?

If your window AC unit needs a quick tune-up, then this guide can help.

Below, we’ll show you the top 8 ways for how to make window AC colder.

We’ll start with the easiest fixes first and then move on to some methods that require a bit more tinkering.

By the end, you’ll have a number of tricks to try for how to make your window air conditioner colder.

Note: If you don’t have any luck with these tips, you may just need a new window AC unit. If that’s the case, check out our top rated window air conditioners list to find a model that meets your needs and budget.

Or, if you have a small room to cool, take a look at our guide on the best small room air conditioners.

How to Make Window AC Colder

1. Clean the Air Filter

Sometimes you can get your window air conditioner to blow colder with a  simple fix.

Perhaps the air filter is clogged with dust and dirt, which lowers the airflow and efficiency. And it’s the easiest solution for a window air conditioner blowing warm air

So, you just need to clean it.

When it comes to cleaning the air filter in your window AC, you’ll want to unplug the appliance and then remove the filter.

You can use regular dish soap and warm water for this task.

Add the water and soap to a bucket or sink, and then dip the filter into the solution multiple times to remove the grime. A little scrubbing may be required for a lot of dirt buildup.

Should your AC unit have a foam filter, you can clean it in a similar way. Just make sure to wring it out every time you dip it into the soapy water.

When the filter is clean, rinse it with cool water and then allow it to dry completely. You can then place it back into the AC.

2. Clean the Front Grille

This is another simple thing to try for how to make window AC colder fast.

The grille on the front of your window air conditioner can get dirty, which will impede the airflow.

The less air that can get into the unit, the less air that can be cooled and blown into your home.

You can use the same bucket of soapy water that you used to clean your air filter to clean the front grille.

If you can remove the grille from the unit, then you can dip it the same way you dipped the filter.

If the grille can’t be removed, then you’ll want to use a toothbrush to scrub away the dirt and debris from the surface.

Again, make sure that the air conditioner is unplugged and wait for it to dry completely before plugging it in and turning it back on.

3. Clean the Evaporator Coil

The evaporator coil sits right behind the air filter in your air conditioner. It’s common for dust and other debris to build up on the surface.

If that occurs, then your unit won’t cool down like it used to.

To clean the evaporator coil, you’ll want to remove the air filter to gain access.

You can try vacuuming the coil to see if that gets rid of the dust.

If that doesn’t work, then you can use a toothbrush to gently scrub the evaporator coil.

The most efficient way to clean the evaporator coil is to hose down the inside of your window AC unit.

Taking the entire unit out of the window and moving it outside is the best way to hose it down.

Once again, wait for the unit to be dry before reinstalling or turning it on.

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4. Clean the Condenser

Since part of your window AC unit sits outside your home, it’s exposed to a variety of different elements, including dust, pollen, rain, and other debris.

All of those things can build up on the condenser and make it hard for your window AC to blow cold air.

Like with the evaporator coil, you can take a vacuum to the condenser to remove the filth, use a toothbrush, or hose the outside of your AC unit down.

The condenser is located on the back of the window air conditioner and has small coil fins. It looks almost identical to the evaporator coil that sits on the inside of the unit.

Should you decide to use the hose or a bucket of water to clean the condenser, make sure you pour it over the top of the AC to remove all of the grime.

If you can take the unit out of the window, this will make it much easier to hose down and clean.

However, this isn’t necessary, and you should be able to clean it even if you can’t remove it from the window by vacuuming it or using a toothbrush as previously explained.

5. Straighten the Coil Fins

This another straightforward tip for how to make a window AC unit colder.

The coil fins on your window air conditioner are made from thin, delicate metal—which means they can easily get bent if they’re hit by large dirt particles, heavy rains or hail, or other items blowing around inside or outdoors.

If the coil fins are bent, this restricts the amount of air that flows through your unit.

Remember, when it comes to how to make your window air conditioner colder, you need as much air flowing through it as possible.

Taking the time to straighten the internal evaporator coil fins and external condenser fins can help the AC unit run better and cool the air more efficiently.

The straighten the fins, you’ll want to buy and use a fin comb. This tool is specially designed for this task and costs about $10.

All you do is comb through the fins with the tool and it straightens them out. It’s really that easy to use.

6. Clean the External Grates

If the external grates on your window AC unit are dirty, it won’t be able to vent properly.

Thus, vacuuming the dirt and debris from the top and sides of the unit is beneficial.

You might also consider spraying it down with a hose to remove the grime from the exterior.

You can do this with the unit still installed in the window if you can reach it. Otherwise, take the unit down and move it outside to do a good flush.

7. Mist the Unit with Water

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Text Summary of this Tip

If the air outside is incredibly hot, your window AC unit won’t cool the inside as efficiently.

That’s why it may seem like your window air conditioner isn’t doing much good on the hottest days of the summer.

If you find that your AC isn’t cooling as well as it used to, this could be because the outside air is too hot, and the unit needs some help.

This DIY trick to make your window AC colder requires four things:

  • A water hose connected to an outside faucet
  • A garden sprayer connected to the hose
  • A brick
  • A roll of duct tape

To set up the DIY misting tool, follow these steps:

  • Hold the brick vertically.
  • Change the spray head to the mist setting.
  • Lock the spray handle so it’s constantly spraying.
  • Place the sprayer handle on top of the brick.
  • Use duct tape to secure the handle in place so the spray head is pointing down.
  • Set the contraption on top of your AC unit so that the spray head is pointed at the vent with a hole that leads directly into the unit.
  • Turn the faucet on and let the spray head mist your window air conditioner.

Don’t worry about water damaging the inside of your unit. Every time it rains, water gets into this opening, so your hose won’t hurt it.

Check the back of the condenser and look for water running down the fins. If you see this, then you know that you’re misting it correctly.

The air that is being blown into your home should now feel colder.

This DIY method cools down the window AC unit so that it can deliver cooler air indoors.

8. Bypass the Thermostat

Video Version of this Tip

Text Summary of this Tip

The thermostat that came with your AC might not work as well as you had hoped.

In some cases, it will shut the unit off before it reaches the desired temperature.

This means that it won’t keep the room as cool as you would like.

To get around this, you can try this DIY hack that uses a WILLHI WH1436A temperature controller to bypass the thermostat.

You can connect this controller to the compressor, giving you direct control over the temperature.

You can program the WILLHI to turn on and shut off when it reaches a certain temperature.

You can also set a delay for when the compressor turns back on to reduce the chances of the unit freezing up and an overload.

By plugging the temperature controller directly into the compressor and putting the temperature probe behind the original temperature probe, you can make your AC as cold as you want.

How to Make Window Air Conditioner Colder Summary

We hope you enjoyed this guide on how to make window AC colder.

You now have at least eight tips to try to make your window air conditioner blow colder air.

As we mentioned at the beginning, if these tricks don’t work for you, then you may need to buy a new unit.

If that’s the case, check out our top rated window air conditioners list to read reviews and compare the best window AC units available.

We also have a guide on the best small room air conditioners, if you want to get something for a smaller bedroom, living room, or apartment.

Stay cool!

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About David Morrison

David is an Air Quality & Comfort Technician. He has expert knowledge on the technology and design of air purification, air conditioning, and heating systems. His main role is to write content that helps people get the most value out of their air purifiers, air conditioners, and heating units. (See Full Bio)