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Air conditioner on side of house in Fort Collins, CO

You have become familiar with how your AC unit sounds after years of operation, so a new buzzing noise coming from the indoor or outdoor unit may startle you. Learn some of the potential causes for air conditioner buzzing and whether you need a professional HVAC technician to repair it.

Electrical Issues

An underlying electrical problem is the most likely reason for an air conditioner to buzz. If the electrical current escapes its intended path and jumps between circuitry, arcing (and buzzing) can occur. Other electrical problems besides arcing may also be to blame, including:

  • Loose wiring
  • Damaged or failing condenser motor
  • Malfunctioning compressor
  • Faulty contactor relay switch
  • Bad capacitor

Any of these problems may develop as a normal part of wear and tear that occurs over time. Continuing to run your air conditioner in this state could damage other components, leading to costly repairs and possibly putting your family at risk. Therefore, if you suspect an electrical problem, turn off your air conditioner and call an HVAC technician right away.

Frozen Evaporator Coils

The evaporator coils are located in the indoor portion of your central air conditioner. At this stage in the cooling cycle, the refrigerant is very cold, allowing it to absorb heat from indoor air. However, low airflow or a low refrigerant charge disrupts the heat transfer process. The coils may freeze over, generating a low buzzing noise.

If you hear buzzing and find ice buildup on the evaporator coils, turn off the AC until the ice melts. In the meantime, change the air filter and open all return and supply registers. If the coils freeze over again despite your efforts to improve airflow, this means you probably have a refrigerant leak. Only a qualified technician can repair the leak and recharge the system, so it’s time to schedule AC repair.

Loose Parts

Air conditioners vibrate slightly when they operate. Over time, this can cause some parts to shift, loosen, and rattle around. Depending on what has come loose, you may hear a buzzing or shaking sound.

Loose parts can sometimes affect the performance and efficiency of an air conditioner, so you should have the problem repaired as soon as possible. A licensed technician is the only person qualified for the job.

Malfunctioning Condenser Fan

The condenser fan located in the outdoor unit helps exhaust heat to the exterior, cooling the refrigerant before it circulates back inside to collect more heat. When the AC unit kicks on, the outdoor condenser fan should start spinning. If something is wrong with the fan, you may hear a loud buzzing noise.

The problem may be easy to fix. First, check for debris that may have lodged itself in the condensing unit and blocked the fan blade. If you don’t see any obstructions, that means loose parts or a failing fan motor could be to blame. You’ll need a technician’s expertise to help you diagnose and solve the problem.

Damaged Isolation Feet

The compressor is the heart of any air conditioning system. It’s responsible for pumping refrigerant in and out of your home, extracting heat from the air in the process. The compressor is located in the outdoor unit and held in place by rubber isolation feet. As your air conditioner ages, the isolation feet may deteriorate, causing the compressor to become unstable. The resulting vibration may cause an unsettling buzzing noise when the AC runs.

The best course of action is to call an HVAC technician for help. This professional should be able to tell if the isolation feet have worn out or if another problem is to blame for the buzzing you hear.

Not Sure If it’s a Buzzing Noise?

Sometimes, it can be hard to name the type of sound your AC unit is making. Here are some other possibilities besides buzzing that may more closely describe what you’re hearing:

  • Squealing could mean the compressor or fan motor is damaged.
  • Banging or clanging may be the result of a broken compressor.
  • Clicking signifies an electrical issue or debris in the motor housing.
  • Hissing indicates a significant refrigerant leak.

Call Allen Service if Your AC is Making a Buzzing Noise

Still can’t figure out why your AC is making a buzzing noise? Don’t sweat it—call Allen Service for air conditioning repair in Fort Collins! Over the past six decades, we have built a reputation for providing quality work, affordable prices, and unbeatable customer service. Call us today at 970-484-4841 or contact us online if you hear your cooling system buzzing or making other unusual sounds. We’ll diagnose and repair the problem to ensure your home stays cool and comfortable all summer long.