How To Fix AC Running But Not Blowing Cold Air?

Your home is getting hot, the AC is running but not blowing cold air. What do you do if your central home A/C system is not working properly? If you’re wondering why your air conditioner isn’t blowing cool air, here are some possible explanations. If the AC thermostat setting is wrong, it will stop blowing cold air. Other reasons could be that the air filter needs changing or dirt or dust may be blocking air flow on the coils.

What Can Cause The Air Conditioner To Stop CoolingWhat Causes AC To Stop Cooling?

Air conditioning systems rely on many different components to run and cool efficiently. A typical air conditioner has many parts, including an indoor air handler unit (a furnace or fan coil), an evaporator coil, and copper tubing that connects the indoor/outdoor units. There are many answers to the question of “Why is the air conditioner not cooling?”. We will explain and give you the best solutions to the most common reasons for AC not blowing cold.

What causes an AC to stop blowing cold?

Air filter dirty

1. One of the first things to check if your AC is not blowing cold air is if the air filter needs to be cleaned or changed out. Change the A/C air filter if it is dirty to let air flow through efficiently. If you have a clogged AC air filter, the AC cannot properly pull the air through it and this will cause the AC to not cool. AC air filter replacement website here

Thermostat set wrong

2. The thermostat that controls your AC unit may be set to HEAT or to FAN ONLY. Make sure it is set to COLD or COOL. You may have also set the temperature on your home thermostat to a temperature higher than the temperature in your home. This will cause the AC to not blow cold air or even turn ON. Check that the thermostat is programmed and set properly. Refer to your home AC thermostat manual for any issues with programming.

Dirty or blocked coils

3. If your AC is running but not getting cold temperatures inside, another issue may be a blocked condenser coil. The lack of cold air coming from your air conditioner could be because the coils are covered in dust, dirt, or another item blocking it. These coils need to be clean to run properly. Clean the coils of any dust or dirt as any debris buildup or blockage will reduce the efficiency of your AC and will not blow cold air.

AC circuit breaker tripped

4. A circuit breaker may have tripped due to an overload of power usage. Check the AC breaker in the breaker box to be sure the electrical power to the AC is ON. If the breaker has been tripped, reset the breaker and observe the AC unit. There may have been a temporary overload and resetting the breaker will fix the problem.

Refrigerant leak causes no cold air

5. The refrigerant in your AC system is a chemical that is needed to cool the air. A refrigerant leak can cause the AC to not blow cold air. A clue that a leak has occurred is your AC system may be that is runs for a long period of time but does not cool your home. Leaking refrigerant can also cause damage to the compressor and cause the AC system to shutdown. Call a professional if you find a leak.

Compressor or capacitor issues

6. The AC compressor or another component could on the fritz. If the compressor stops working the first thing to check is the capacitor. The capacitor is a coke can sized component in the outside condenser unit. If this capacitor is faulty, the compressor will not run. Check the capacitor with a meter and remove and replace it out if you find it to be faulty. If capacitor is OK then you need to check the compressor itself.

AC unit is undersized

7. All AC’s are labeled by the amount of cooling they can produce. This label is called BTUs (British Thermal Units). If the temperature outside is a mild heat temperature, the AC may run fine. However, when the heat outside rises, your AC may not be able to keep up. This could mean that your AC unit is undersized for the amount of space in your home you are cooling. Check the BTUs of your AC unit and compare it to the square footage of your home. Your AC unit may not produce enough BTUs to cool your home. If this is the case, consider getting a bigger sized BTU AC unit.


How To Check Air Conditioning When Blows Hot Air

Window air conditioner not cooling

8. If you have a window air conditioner in your house, to cool a room properly, make sure the window AC is installed properly and that air can circulate around it. If the window AC is not installed properly, it will not cool as designed. Make sure the seal around the window AC is not letting in any hot air from outside. Be sure there is nothing to close to the window AC unit so air can circulate as needed.

If you have an older AC unit with a compressor that is having problems or you just cannot figure out why the AC does not blow cold, then the AC may need professional maintenance. There are many other possible causes for the not blowing cold air issues. Some are quite complex and and we recommend contacting a professional HVAC service company to give you a quote if the above info did not solve you problem.

How Does An Air Conditioner WorkHow Does An AC Work?
Image credit: Pinterest

NOTE: Remove power to the AC when troubleshooting. Some AC repair should always be done by a professional HVAC – Heating Ventilation Air Conditioning expert. Changing out a faulty capacitor for the compressor is an easy job if you know what you are doing. If you know you have air conditioner compressor issues, it is best to call a professional to come have a look and give you a quote.

Have questions after trying all the above common methods for fixing your AC to blow cold air? Leave a comment below with how we can help you, please give us your AC unit model number and your thermostat type.

ALLEN VETTER - DIY Repair Assistant
Allen is a Home Maintenance/Appliance Tech and the author/creator of this website. He has 33 years of experience troubleshooting and repairing all types of appliances. Contact here

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