Air Conditioner Not Blowing Cold Air? Why & How to Fix It

If your AC is running but not cooling, it could be due to common issues like a dirty filter, thermostat settings, or low refrigerant. Find out what to do next!

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Oct 10, 20240 comments

10 Reasons Your AC Runs but Doesn’t Cool

Dirty Air Filter

A clogged filter reduces airflow, forcing your AC to work harder and possibly causing frozen coils. Replace or clean it every 1-3 months.

Incorrect Thermostat Settings

A simple thermostat error, like being set to “fan” mode or too high a temperature, can prevent cooling. Ensure it's on "cool" and set below room temperature. Low batteries might also be the issue.

Refrigerant Leak

Refrigerant is what absorbs the heat from inside your home and releases it outside. An air conditioner refrigerant leak reduces cooling efficiency, leading to warm air or hissing sounds. A professional is needed to repair and refill refrigerant.

Blocked Condenser Unit

The condenser unit is the part of your AC that’s outside. Its job is to release the heat that’s been absorbed from inside. Leaves or debris around the outdoor condenser restrict heat release. Clear the area and hose down the fins (the metal strips around the condenser) to restore proper function.

Frozen Evaporator Coils

The evaporator coils inside your AC absorb heat from the air to cool it. Frozen coils prevent heat absorption, often due to restricted airflow or low refrigerant. Turn off the AC, let the coils thaw, and check the air filter.

Faulty Compressor

The compressor is like the heart of your AC. It pumps and circulates refrigerant through the system. A faulty compressor will stop cooling. A broken compressor often needs to be replaced by a professional.

Electrical Issues

Your AC relies on several electrical components to function. If there’s a blown fuse, a tripped breaker, or a damaged capacitor, it can keep the AC running without actually cooling. Electrical issues can be tricky so it’s best to call in a technician to inspect and fix any damaged electrical components.

Ductwork Leaks

Ducts carry the cool air from your AC throughout your home. Leaks in ductwork let cool air escape, reducing efficiency and increasing bills. A professional can seal leaks to ensure proper cooling.

Aging or Undersized AC Unit

Older units, or those that are too small for the space they’re cooling, struggle to keep up on hot days. If you’re considering a mini split, it’s essential to ask, what size mini split do I need, to ensure it’s correctly matched to your space for efficient cooling.

Blocked or Closed Air Vents

Closed or blocked vents restrict airflow, causing uneven cooling. It’s easy to accidentally close a vent while cleaning or arranging furniture. Walk through your home and make sure all vents are open and unobstructed.

A technician is using a water gun to clean a mini split air conditioner that is blowing air but not cooling.

Troubleshooting Different Types of Air Conditioners

The causes of cooling issues of each type of air conditioner can vary depending on the model you have. Here’s a breakdown of specific issues and troubleshooting tips for common types of air conditioners:

Portable Air Conditioner Not Blowing Cold Air

Check Placement

Ensure the unit has ample clearance on all sides and is not too close to walls or other obstructions.

Inspect the Exhaust Hose

Make sure the exhaust hose is properly vented outside and securely connected, allowing warm air to escape the room effectively.

Window Air Conditioner Not Blowing Cold Air

Clean the Filter and Coils

Unplug the unit and check the air filter. Clean or replace it if it’s dirty, and wipe down the coils to improve airflow. For those sensitive to noise, cleaning the window AC air filter could also get an ultra quiet AC window unit.

Ensure a Tight Seal

Verify that the AC is sealed tightly in the window frame to prevent warm air from leaking in around the edges.

Mini Split Air Conditioner Not Blowing Cold Air

Clear the Outdoor Unit

Check for any debris, like leaves or dirt, around the outdoor unit and clear it away to maintain proper airflow.

Check Refrigerant Levels

Low refrigerant is a common issue with split ACs, but this requires a technician to refill and inspect for leaks. Also, check that the mini split AC indoor unit’s filter is clean and replace it as necessary.

Central Air Conditioner Not Blowing Cold Air

Verify Thermostat Settings

Make sure the thermostat is set to “cool” mode and the temperature is set lower than the room temperature.

Inspect Ductwork and Vents

Look for visible leaks or blockages in the ducts, and ensure all vents are open and free from obstructions.

Consider Professional Help

If these steps don’t resolve the issue, central AC problems often involve complex components, so it’s best to have an HVAC technician perform an inspection.

Tips for Optimizing Cooling in Your Home

If you want your AC to cool your home more effectively, consider these practical tips:

Use Ceiling and Portable Fans

Fans help circulate the cool air, making rooms feel cooler without lowering the thermostat. If you have a mini split system, learning how to clean mini split units properly can also ensure optimal airflow

Close Blinds and Curtains During the Day

Blocking sunlight prevents heat buildup, which keeps your AC from working harder to cool the room.

Seal Windows and Doors

Leaks let in warm air, making your AC less efficient. Use weather stripping or caulk to seal any gaps and keep the cool air inside.

Limit Heat-Generating Activities

Avoid cooking or running heat-producing appliances during the hottest parts of the day. This reduces extra heat that your AC has to cool.

Keep Vents Open and Clear

Make sure all AC vents are open and free from obstructions to allow cool air to flow freely throughout the home.

Adjust Thermostat Fan Settings

Set your fan to “auto” instead of “on” so it only runs when cooling, which can help your home cool down more efficiently.

Use a Programmable Thermostat

Schedule your AC to start cooling before you arrive home. This way, it doesn’t have to work as hard to cool a hot house.

A technician successfully repaired a mini split air conditioner that was blowing air but not cooling.

Conclusion

Addressing common issues and optimizing your AC’s performance can help you enjoy cooler, more comfortable air in your home. If you’re ready for an upgrade or need a reliable air conditioner, explore Della’s range of high-quality units designed to keep your space cool and efficient. Check out Della's latest air conditioner sale for great deals on top models!

FAQs

Should I turn off the air conditioner if it is not cooling?

Yes, it’s best to turn off the AC if it’s running but not cooling. Continuing to run it can strain the system and potentially cause more damage. Turning it off allows the unit to rest while you troubleshoot or call a professional to assess the issue.

What temperature should I set my thermostat to for maximum efficiency?

Setting your thermostat between 75°F and 78°F during the day can help balance cooling comfort and energy savings. At night, you may prefer a lower setting to enhance sleep quality without overworking the AC.

Is it normal for the outdoor unit to make noise while running?

Some noise is normal, but loud or unusual sounds like banging or hissing could indicate a mechanical issue. If you notice unusual noises, it’s best to have a technician inspect your AC to prevent further damage.

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