What makes a window AC not cool?

Author: Kaelyn Ferry  |  Last update: Friday, January 30, 2026

If your AC is running but not cooling, it could be due to a dirty air filter, incorrect thermostat settings, a malfunctioning thermostat, a refrigerant leak, dirty condenser coils, blocked vents or ducts, a faulty compressor, frozen evaporator coils, or electrical issues.

Why is my window AC running but not cooling?

The problem may arise as a result of dirty air filters, a malfunctioning fan or a refrigerant leak. In order to fix this, you'll need to call the experts. If there are leaky coils, your HVAC technician can replace them.

How do I make my window AC colder?

Identify the temperature sensor on your window AC. Take a regular sock and remove the sensor. Wrap the sock around the sensor twice. Put the cover and filter back on. The AC will now blow colder air.

Can you recharge the Freon in a window air conditioner?

Window AC units can be recharged, but—just like central air—the closed refrigerant system won't need a recharge unless it's damaged. Instead, a well-maintained window air conditioner can last its whole lifespan without needing its refrigerant replenished.

Why is my AC blowing but not getting cold?

If your central AC is not blowing cold air, the refrigerant may be the problem. The unit could be running low and need additional refrigerant added. The most likely cause of this is a leak. A leak not only keeps the AC unit from cooling properly, but also it can cause other issues within the home.

Window Air Conditioner Not Cooling And The Most Common Fix

How to fix an air conditioner that is not cooling?

To fix an AC not blowing cool air, ensure the thermostat is set to "cool" mode and the temperature is set lower than the current room temperature. Inspect the air filter as a dirty filter can restrict airflow. Ensure the condenser coils are clean and free of debris. Make sure vents are open and unobstructed.

How to know if refrigerant is low?

Warning Signs of Low Refrigerant in Your AC or Heat Pump
  1. Weak Airflow or Warm Air Blowing from Vents. ...
  2. Poor Cooling Performance. ...
  3. Constant Cycling On and Off. ...
  4. Ice Buildup on Refrigerant Lines or Evaporator Coil. ...
  5. Hissing or Bubbling Noises.

How do I know if my window air conditioner needs Freon?

AC is running, but the home isn't cool

You might feel warm air flowing through the vents, or you might notice that your AC is weaker than it used to be. If air flow seems fine, but the air coming up isn't cool, then you likely have a refrigerant problem.

How much does it cost to put Freon in a window air conditioner?

Most homeowners will pay in the range of $200 to $400 for a refill, depending on the type and size of their HVAC unit. If you own a larger r22 unit, you may have to spend $600 or more. To break this down for you, a 25lbs unit of r410A costs anything between $100 and $175.

How to reset window air conditioner?

Most ACs have a reset button located either near the power plug or within the control panel on the unit. Simply press this button for a few seconds to reset the unit. Once you have let go of the button, wait ten minutes for it to reset, and then turn it back on.

How long do window AC units last?

Window AC units usually have the shortest lifespan, averaging 8 to 10 years. They are often less expensive but may require more frequent replacement.

How do I get my AC cold again?

Why Is My AC Not Blowing Cold Air? Easy Fix
  1. Introduction. ...
  2. Check the AC unit to make sure it's not running on low refrigerant. ...
  3. Look for debris in the condenser, which is part of the system that pushes air through the vents. ...
  4. If you have a coil unit, check your airflow. ...
  5. Check your filters and replace them if necessary.

Why is my window AC not reaching set temperature?

One possible reason your AC is not reaching the set temperature is that the thermostat could be dirty. If dirt, dust, or other debris has accumulated within the thermostat box, it can cause the wires to heat up or other issues. Thermostats are cleaned during routine HVAC maintenance to help prevent this from happening.

How can I make my window air conditioner colder?

There are a few things you can do to make an air conditioner colder instantly:
  1. Turn off electronics and appliances that generate heat.
  2. Close blinds or curtains to block out sunlight.
  3. Replace old air conditioners with newer, more efficient models.
  4. Make sure the AC unit is sized correctly for your home.

Should I turn off AC if it's not cooling?

When you notice that your air conditioner isn't cooling, your first action should be to turn it off. This might seem counterintuitive—after all, you want your home to be cool. However, continuing to run an AC that isn't effectively cooling can cause further damage to the system.

Can I add Freon to my window AC unit myself?

It's possible to add Freon to your air conditioner unit yourself, but you'll need some general knowledge about ACs and a few specific tools to do it correctly. The process can be dangerous, so hire a qualified professional if you feel unsure about what to do.

Why is AC not blowing cold air?

First, check your filters and coils for dirt and debris that may be impeding airflow. Once you've cleaned the filters and coils, run the air conditioner with just the fan so that the ice accumulation can melt off. If the AC still doesn't blow cold air, it could be that refrigerant levels are too low.

Is window AC worth repairing?

A repair may be the top option if the problem is minor, such as a faulty thermostat or an old air filter. However, if the problem is more significant, such as a failing compressor or a leak in the refrigerant line, it may be cost-effective to replace the Unit.

How long does Freon last in a window air conditioner?

The Reality: Freon is Forever

Air conditioners are closed systems.

Can an AC unit lose Freon without a leak?

Refrigerant is a working chemical that runs through your car's A/C system in either a gaseous or liquid form. Causes of refrigerant leaks in your vehicle include physical damage, wear and tear over time, and escaping refrigerant even without a leak.

How to tell if AC needs recharge or new compressor?

How to Tell if Your Car A/C Needs Recharging
  1. Your car is blowing warm or hot air instead of cold. ...
  2. Your car is visibly leaking refrigerant. ...
  3. The A/C clutch is not engaging. ...
  4. There's a weird smell coming from your vents.

How to check refrigerant level in window AC?

Steps for Checking Refrigerant Levels
  1. Turn Off the AC and Remove the Cover. Turn off the AC unit and remove the cover to access the refrigerant level gauge or gauges.
  2. Locate and Remove the Access Panel. ...
  3. Attach Refrigerant Pressure Gauges. ...
  4. Interpret Pressure Levels. ...
  5. Add Refrigerant (if Necessary)

How to check gas in window AC?

Turn off the air conditioner and locate the service valves. Attach the manifold gauge set to the service valves. Turn on the air conditioner and observe the pressure readings, which should be between 30-40 PSI for most systems (though some may require higher or lower pressures).

How to tell if your AC unit is out of Freon?

Symptoms of Low Freon in a Central Air Conditioner
  1. AC Takes Longer to Cool Home. ...
  2. Utility Bills are Higher than Normal. ...
  3. Air Coming From Vents Aren't Cold. ...
  4. Ice Built Up on the Refrigerant Line. ...
  5. Strange Noises from AC. ...
  6. Contact Day & Night Air Conditioning For Freon AC Help Today!

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