Why is my outside AC unit not cooling?

Author: Prof. Katarina Toy  |  Last update: Thursday, August 28, 2025

There are a number of reasons why your air conditioner might be running but not cooling. It could be an issue with the thermostat, the compressor, or the evaporator coils. Or, it could simply be clogged with dust and debris, which is preventing it from working properly.

Why is my outside AC unit running but not cooling?

In some cases, clogged air filters or dirty evaporator coils can also restrict airflow, forcing the AC to compensate by running at high power. To resolve this issue, it's recommended to check for clogged filters, clean coils, and consider having a professional inspect and repair the motor or fan control components.

How do I know if my AC is low on freon?

Signs your AC is Low on Freon
  1. It Takes Much Longer Than It Should to Cool Off Your Home.
  2. Your Utility Bills Are Higher Than Usual.
  3. The Air Coming Out of Your Vents Isn't Cold.
  4. Ice Has Started to Build Up on Your Refrigerant Line.
  5. You Hear Loud or Unusual Noises Coming From Your Unit.
  6. Hissing or Bubbling Noise.

How do I reset my outside AC unit?

In AC systems, the air conditioner reset button is on the outside unit's lower edge, typically close to the ground. Some models have the reset button located behind the service panel, which may require tools to remove. Reset buttons are usually red or yellow with a clear “reset” label.

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

Switch it off. There's no need to be using it if it's not cooling so it's just a waste of electricity. And in some cases such as a freeze up it'll make the technician have to stay longer to fix it because he would have to wait for the ice to melt.

How to Fix Air Conditioner Not Blowing Cold Air | HVAC Training 101

How to fix AC unit 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 it better to turn off AC or raise temperature?

While you might be tempted to simply turn the AC off, it's actually better to adjust the temperature several degrees higher, by about 7-10 degrees. By installing a programmable thermostat and making this simple adjustment you can potentially save as much as 10% on your energy bill.

Why is the outside of my AC not working?

Make sure the outside unit is turned on (there's probably a switch near the unit). If the outside unit has a separate circuit breaker, check your circuit box and make sure it hasn't been tripped. A more serious issue if the outside air conditioning unit's not working is a broken compressor, capacitor or fan.

Where is the reset button on a carrier outside AC unit?

FIND THE RESET BUTTON

In most cases, the small red reset button is inside the AC's compressor. If unsure, you can always refer to the user's manual to find the exact location.

Can resetting the breaker fix AC?

In the majority of cases, your AC system will return to functioning normally after this breaker reset. It's important to know that this isn't an instant fix and may take up to an hour to get back up and running as normal again.

Can AC lose refrigerant 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 much does it cost to refill Freon in an AC unit?

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 do I check the Freon in my home air conditioner?

Steps to Check Refrigerant Levels
  1. Turn off the air conditioner and locate the service valves.
  2. Attach the manifold gauge set to the service valves.
  3. 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).

Should my outside AC unit be blowing cold air?

If your air conditioning unit is ac blowing cold air outside, it might mean there's a problem with cooling the air inside. This could be due to refrigerant leaks, frozen coils, electrical issues, or airflow problems. It's important to find out why to fix it and keep the cold air inside.

What is the first thing to check when the AC stops working?

Check these issues when the unit won't kick on: Check the thermostat and adjust the settings if it isn't set to Cool and an appropriate temperature setting to call for cooling. Examine the house circuit breakers for the AC unit and reset any tripped breakers. Check the air filter and replace the filter if it's dirty.

How to unclog a condenser coil?

What Is the Best Way to Clean AC Coils?
  1. Step 1: Turn Off the Power to Your Air Conditioning System. ...
  2. Step 2: Remove the Outer Cover of the Air Conditioning Unit. ...
  3. Step 3: Clean the Coils and Fins. ...
  4. Step 4: Apply Coil Cleaner. ...
  5. Step 5: Rinse the Coils and Fins. ...
  6. Step 6: Let the Coils Dry.

Is there a way to reset outside AC unit?

Check For An AC Reset Button

Some systems have a reset button on the unit that'll perform the resetting process for you. To check if your system has this button, you'll need to look for it on your outdoor unit. Usually, it's a large red button.

Why is my carrier air conditioner not cooling?

Carrier air conditioner is not blowing cold air

Make sure your thermostat is set to “auto” and “cool.” Check if your air filter is clean. If not, replace your AC's air filter. If that doesn't solve the problem, your refrigerant may be low or there could be a leak in the evaporator coil.

How long to leave AC unit off to reset?

Shut off your system by hitting the isolation switch, wait 30 to 60 minutes and then turn it back on. This manual reboot fully disconnects your AC unit from power, allowing all electrical components to reset.

Why is my outside unit not running but inside is?

When the outside unit breaks down but the inside unit is running, the culprit may well be a broken compressor in the outside unit. That's typically a major repair, something that might even warrant a system replacement.

Why would AC be running but not cooling?

There are a number of reasons why your air conditioner might be running but not cooling. It could be an issue with the thermostat, the compressor, or the evaporator coils. Or, it could simply be clogged with dust and debris, which is preventing it from working properly.

How do I know if my outside AC fuse is blown?

If you think your air conditioner has blown a fuse, the first sign you'll notice is that the outside AC unit is inoperable. The best way to check for a blown fuse is by using a voltmeter. Be warned — you are working with live electricity and should use extreme caution when troubleshooting your system.

Is 72 too cold for AC?

While the standard room temperature of 72 degrees Fahrenheit is commonly favored by many, others argue for higher settings, particularly when it's hotter outside.

Do you turn AC up or down to make it colder?

Most people know that turning up the thermostat on their air conditioner to a higher temperature will result in cooler air blowing from the vents. However, there is a point at which increasing the temperature any further does not make the air cooler – it just uses more energy and costs more money.

Why is my thermostat cool but AC not turning on?

Sometimes, the thermostat simply has dead batteries or a wiring issue that is preventing it from sending the correct signal to the AC unit. Replacing the batteries or checking the wiring may solve the problem. If the thermostat malfunctions completely, it may need to be replaced to restore the AC's functionality.

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