Why does my AC sound like it's running but no air?

Author: Helmer Jenkins  |  Last update: Friday, November 21, 2025

If your air handler is running but not blowing air, there are two likely scenarios: either a broken AC blower belt or an issue with the motor itself. If the air handler is humming or buzzing but not making the mechanical sounds of a motor running, you're most likely talking about an issue with the motor itself.

Why is my AC fan running but no air through vents?

If your AC unit and furnace fan is running but you still have no airflow your most likely have a frozen evaporator coil. Caused by either an airflow issue like plugged air filter or plugged evaporator coil. Or your AC unit could have a refrigerant leak and be low on charge.

Why is my air conditioner making noise but not working?

An AC unit humming but not turning on is often caused by a faulty capacitor, a tripped circuit breaker, or a malfunctioning compressor. When the AC capacitor fails, the fan motor does not receive power, resulting in a noticeable humming or buzzing sound.

Why does my AC click but no air?

Most commonly this is due to dead blower fan start capacitor. Turn off AC ASAP, allow frozen inside coil to defrost. Remove blower fan capacitor and test capacitance. Replace if needed.

Why is my AC unit running but no fan?

If your AC unit is running outside but not the fan in your furnace you most likely have an issue with the control board or fan relay in your furnace, a bad fan motor, or possibly a bad capacitor on your furnaces fan motor.

5 Common AC Noises and What They Could Mean

Why is my AC running but no airflow?

If your air handler is running but not blowing air, there are two likely scenarios: either a broken AC blower belt or an issue with the motor itself. If the air handler is humming or buzzing but not making the mechanical sounds of a motor running, you're most likely talking about an issue with the motor itself.

Why is my AC unit making noise but fan not spinning?

First, you notice there's warm air coming from your vents. Then, you hear a humming or buzzing sound coming from your outdoor AC unit, and you see that the fan isn't spinning. Does this describe your situation? If so, it probably means you have a bad fan capacitor.

Why is my fan running but no air?

If your ceiling fan isn't blowing air, one potential reason is electrical issues. This can be caused by a variety of factors including a blown fuse, loose wiring, a problem with the dual or single capacitors, or a defective motor.

Why is my AC 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.

Should the outside fan run when AC is on?

The short answer: Definitely not. (Unless you have manually engaged your outside fan to run constantly, but it shouldn't be running for hours on it's own.) If your HVAC is functioning correctly, it should keep your house cool by cycling on for 15-20 minutes at a time—with distinct pauses in between each cycle.

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.

Why is my compressor humming but not starting?

If the capacitor is faulty or damaged, the motor may struggle to start, resulting in a humming noise. Loose or Damaged Wiring: Loose or damaged wiring can disrupt the flow of electricity to the motor, causing it to hum without starting properly.

Why does my air conditioner turn on but nothing happens?

You go to turn on your air conditioner but nothing happens. Why? Usually, it means that your system is not receiving power or that your thermostat is not set correctly. Make sure that your thermostat is set to “cool.” You may also need to adjust the temperature that it's set to.

How do I know if my AC vents are clogged?

You can generally identify a blocked air duct by a distinct drop in heating and cooling efficiency, increased energy costs, and occasionally a musty, dusty smell throughout the home. The blockage usually comes over time, by a buildup of dust and debris that just accumulates until it begins choking the system.

How much does a compressor cost for an air conditioner?

On average, AC compressor costs range from $800 to $2,300, with most folks paying $1,200 for a new one. However, your price will vary depending on factors like the size and brand of your compressor. Before you schedule your replacement, read on to learn about all AC compressor cost factors.

How do I fix my AC not blowing air?

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.

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

Turning off your AC when it's not cooling is more than a precaution; it's a necessary first step in troubleshooting and protecting your system from further damage. By understanding when to perform simple checks and when to call in the experts, you ensure your air conditioner remains a reliable refuge from the heat.

How do I reset my central AC not blowing cold air?

Use these tips to reset an air conditioner using the reset button:
  1. Turn your thermostat to the “off” setting.
  2. Turn off the circuit breaker that powers your AC.
  3. Press and hold the reset button for three to five seconds.
  4. Restore power to your AC by flicking the circuit breaker back on.

Why is my fan running but not my air conditioner?

Check Your Circuit Breaker

When the fan is turning but the air conditioner's compressor is still, another likely problem is that electricity isn't traveling to the outside unit. The compressor is outside, thus, it's still, but the fan is still connected to the interior power.

Why is my fan humming but not turning?

If your ceiling fan stopped working but the light still works, check for a humming sound. This could be indicative of a blown motor capacitor, which is often caused by overheating. While inspecting the motor housing, look for a small black box connected to the pull cord.

Is it OK to run just the fan without AC?

Even with the AC off, running the fan helps circulate air. You might not need cooling, yet your house feels stuffy. Running the blower can increase ventilation without turning on the AC and consuming more electricity. That's if you don't keep the blower running for too long.

Where is the reset button on an AC unit?

Power down your AC: Turn off your AC unit and unplug it from the power source. This will ensure that you stay safe while working on the unit. Locate the reset button: Most air conditioning units have a reset button located near the outside unit. It is usually a small button located inside a small hole.

Why is my AC fan running but no air coming through vents?

Check Your Air FilterOn the opposite side, if your AC and fan are both running and you still are not getting airflow through your vents, you will want to check for a dirty air filter. The air filter collects dust and debris and can block airflow through your system if not changed routinely.

How to tell if an AC capacitor is bad?

A sure sign of a bad AC capacitor is a humming sound from within the access panel. Any humming noises indicate a problem with the air conditioning system or the components of the AC unit. Try turning the power on and off again to see if it was a one-time issue with the motor or a recurring problem.

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