Why Is My AC Making a Buzzing Noise?

A number of common issues can cause your AC to start buzzing, with the most common including:

• Loose parts or vibrating components. Any number of loose parts can create vibration while running.
• Electrical issues. Buzzing can originate from faulty capacitors, failing contactors, or even loose wiring.
• Frozen evaporator coils. Ice buildup around the evaporator coil results in an uneven weight distribution, which can vibrate and buzz while the blower motor runs.
• Refrigerant leaks. If refrigerant leaks from your AC, the internal components may freeze, causing them to vibrate more and creating a buzzing noise.
• Compressor problems. Issues with the compressor, such as misalignment, looseness, or issues with the bearings, can all cause buzzing and vibrating.
• Debris in the outdoor units. Sometimes, twigs, leaves, and dirt can find their way inside the outdoor unit, leading to buzzing.

Before rushing to call an HVAC tech, you can try to resolve the issue yourself using some simple DIY troubleshooting steps:

1. Turn off the AC unit at the breaker and thermostat to prevent further damage.
2. Inspect the outdoor unit for signs of damage, debris, bent fan blades, or loose panels.
3. Check the air filter for potential clogs that could freeze the system's coils.
4. With the system running, listen for any additional noises. Clicking or humming alongside buzzing could mean electrical issues or failing capacitors that need attention.
5. Try turning off and restarting the system for a few minutes. Sometimes, this is enough to stop minor buzzing.

If you notice persistent buzzing even after these steps, you should have a professional inspect the system.

Sometimes, there's no way around needing professional intervention. If you suspect these issues, contact your local HVAC company as soon as possible:

• Electrical malfunctions. If you hear buzzing sounds from the electrical panel, compressor, or inside the unit, having a trained tech inspect things is a good idea.
• Refrigerant leaks. Don't attempt a DIY repair on refrigerant links. Specially trained technicians must handle these.
• Compressor failure. Compressors often need difficult repairs or outright replacements when they're buzzing. This is best left to the professionals.
• Persistent buzzing after troubleshooting. If you've gone over the common causes and noticed the buzzing continues, have a professional perform an inspection.

Regular preventative maintenance steps can help keep your system running effectively and quietly.

• Schedule regular tune-ups to identify and remedy minor issues. Ideally, your AC should be serviced annually at a minimum.
• Replace air filters as recommended, usually every 1 to 3 months. This prevents airflow restrictions that can add extra strain to the system.
• Regularly ensure the outdoor unit is clear of dirt, debris, and leaves.
• Inspect wiring connections to make sure nothing is loose or damaged.
• Check refrigerant levels regularly to avoid compressor strains and confirm there are no leaks.