Why a Window Air Conditioner is Not Blowing Cold Air

By | June 7, 2023

Window Air Conditioner Not Blowing Cold Air Troubleshooting
There are many reasons a window air conditioning unit is not blowing cold air, from a dirty filter to simply being worn out.

Below are the seven most common reasons why a unit stops blowing cold air into a room.

If you have a unit that is not working and the cause is not on the list, let us know in the comments below.

7 Reasons a Window Air Conditioner is Not Blowing Cold Air

  • Be Sure the Thermostat is Set Low Enough
  • Reasons a Window Air Conditioner Unit is Not Blowing Cold Air Thermostat
    Make sure the thermostat is set correctly for cooling. This may seem obvious, but it happens.

    Check the thermostat on your unit and be sure the temperature is set low enough for it to kick on.

  • Dirty Air Filter
  • Window Air Conditioner Not Blowing Cold Air Cleaning the air filter
    All air conditioner units need good airflow to work properly.

    A dirty air filter can block airflow and cause a unit to stop working properly.

    The air filter is usually located inside the front cover, and each unit has its own procedure to replace or clean it.

    Read Here for How To Clean a Window Air Conditioner Filter

  • Clean the Outside Fins of any Debris
  • Window Air Conditioner Not Blowing Cold Air
    The outside fins are there to dissipate heat as the outside fan blows air through them, much like a radiator in a car.

    If the fins become clogged, they can stop dissipating heat, and the unit will stop working.

    A quick way to fix this is with the unit off, and use a hose to blow out anything that may be blocking the fins.

    Be careful not to bend the fins as they are easily bendable and will restrict the airflow if bent.

    Read Here for How to Clean a Window Air Conditioner

  • Clean the Inside Coil
  • Room air conditioner Reair Cleaning
    The inside coil can become dirty, the same as the outside coil, and need to be cleaned.

    The inside faceplate cover will likely have to be removed and will depend on the unit how this is done.

    Don’t use any chemicals to clean the inside coil as they will smell as they are blown into a room.

    Use plain water and clean the dust or any build-up that has occurred.

    Again be careful not to bend the small fins.

    Read Here for How To Clean the Inside Coil on a Window A/C Unit

  • Check if the Outside Condenser Fan is Blowing Air
  • Window Air Conditioner Check outside Fan
    It is easy to tell if the inside fan is blowing, but there is also an outside fan that blows hot air away from a unit.

    If the outside fan stops blowing, the unit will not work.

    Some outside fans work only intermediately and shut off to save energy when not needed. Most Window A/C units use the same motor to turn the inside and outside blades, but they can be separate.

    There is no need to open the unit up to see if it is turning, as you should be able to feel the air moving past the outside of the unit.

    Be sure to check the outside fan when the unit is not working since it should be on and blowing hot air away.

  • Does the Compressor Turn On?
  • Window Air Conditioner Not Blowing Cold Air Check Compresor
    The compressor makes a clunk and noisy buzzing sound when it turns on.

    It is basically a pump that cycles the refrigerant throughout a unit.

    It is usually noticeable if a compressor has gone bad since the noise the unit makes will have changed.

    Read Here for More on A/C Compressors

  • Low on Refrigerant
  • Troubleshooting a Window Air Conditioner Not Blowing Cold Air 7
    Window AC units can become low on refrigerant and need a charge to begin cooling again.

    Usually, a unit low on refrigerant will be replaced, but they can have refrigerant added back into the system.

    Some skills and basic tools will be needed to get a unit recharged.

    Read Here for More on How To Recharge a Window Air Conditioner Unit

Once general maintenance and main components are checked, if a unit is still not working, it is likely time to replace it.

A professional can be called to fix it, but it is likely not worth the effort since the cost is usually more than replacing the entire unit with a new, more efficient model.

There are many affordable options even quiet units if a new unit is needed.

Have you had problems with a window air conditioner not blowing cold air? Let us know your thoughts below.

Category: window mounted air conditioner

About Aaron H. Benetti

Aaron H. Benetti an HVAC technician who has worked in the field since 1991. He began his career as an HVAC installer and later began doing troubleshooting and repairs. Around 2010, he began to write books on HVAC topics, mainly tutorials and how-to information. Currently, Aaron works as an HVAC tech and also writes many articles and posts for websites as well as books and videos on HVAC topics.

13 thoughts on “Why a Window Air Conditioner is Not Blowing Cold Air

  1. Elmey J

    Does an ac compressor tend to be hot? Or a well working compressor always stay cool? Whats the max temp for a running compressor?

  2. kevin

    HI! my name is KEVIN, please tell me, how to set number on thermostat when opend coolair, from 1 t0 9 (which one has coolest for the goldstar coolair conditioner install on wall place.thanks so much. and what’S funtion the bar under the shiel ( can be set swing) use for what? thanks for reply

  3. Kay Hambers

    My window unit is blowing cold air a little and it is blowing cold air out the back also. When it’s supposed to blow hot air out the back. Why is this ?

  4. Julie herrington

    My ac unit runs blows cold air but compressor turns on and off to much got it on 64

  5. Montez R

    Hey how do you reset the whole unit itself I’m having problems lowering the thermostat so I can get the cold air thank you

  6. Matt

    Excellent read, now I’m comfortable that the humming noise accompanied by fans running should be the fan motor. I of course just mounted and sealed the air conditioner into the window for the summer, so yay that it worked fine for 3 hours and THEN broke. But better than when it’s 90’s all week.


    None of that helps I got my new window a.c. 1 day ago I got 2 the one works fine the other isn’t blowing out cold air

  8. Montez R

    Hey how do you reset the whole unit itself I’m having problems lowering the therm0sat so I could get the cold air thank you

    1. D J Thompson

      My Haier window a/c thermostat was stuck on 84, I cleaned the front and back coils, cleaned the filter and attempted to reset by pressing the reset button nothing helped. The a/c would blow cool air only for a few minutes. I was so frustrated I turned the a/c on and let it run while I cooked in my hot kitchen. The a/c sounded as if it recycled, then started to blow cold air and the thermostat started to work. I guess the combination of heat, steam and my oven caused the room to reach the temperature the thermostat was stuck on. My a/c is working just fine.

    1. Scott

      I have a 18000 BTU Frigidaire window unit 220 volt everything works on it except I have to take my finger and give the fan a little boost and then it’ll start right up what should I check the start capacitor and where is it

      1. Trap

        Just clean the fan motor. It’s a little bit of a pain but well worth it. Mine was doing the same thing. I took the motor apart, cleaned the rotor and the stator. Use a wire brush(not to stiff) or you can use aluminum foil – it works great. If it’s a bigger rotor you can use a Dremel or something like it. Just not to stiff on the brush. Then, when they’re clean, a little light weight oil on the rotor and stator. About 5W20, I used a little 2 stroke oil. And then a little on the shaft also. It’ll run like new!!


        1. Laura and Dwight Johnson

          We paid $1,000. For a unit air conditioner from “Sears”!!! It’s
          blowing hot air instead of cold! We even paid extra for the warranty!! “Looks like we’ll be forced to get a newer ac!!
          sEARS won’t be where we’ll buy it though!!


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