Why is My AC Making a Loud Buzzing Noise? A NJ Tech Explains | Air Experts

If your AC is making a buzzing noise, it’s usually a strong indication that your system is having an electrical issue. 

Outside of an electrical problem, there are a variety of other reasons your AC could be making loud buzzing noises, including:

  • The outdoor unit has loose parts
  • Fan motor is broken or malfunctioning
  • AC unit is frozen 

Below, we’ll walk through each of these problems, so you can get a better idea of what could be causing your AC to make loud buzzing noises. 

Buzzing Noise #1: Electrical Issue

The most common reason your AC would be making a buzzing noise is because of something called “electrical arcing.” Electrical arcing is something that occurs when electricity jumps between circuitry. 

Common AC electrical issues include:

  • Failing motor
  • Malfunctioning compressor
  • Loose wiring
  • Arcing (electrical current escapes the intended path)

Typically, an electrical issue like the ones mentioned above is the result of wear and tear over time. The best way to solve this issue is to contact an HVAC professional and have them come check out (and potentially repair) your AC unit. HVAC pros are the best choice for this job (vs. electricians) because they are trained specially to work on the electrical components of HVAC systems.  

Buzzing Noise #2: Loose Parts

Over time, parts of your AC unit can loosen, causing the rattling or buzzing noise you’re hearing.

If you notice the noise coming from your outdoor unit, this is likely your issue. To fix it, you’ll need to have a technician come to your home and assess your outdoor AC unit. The solution could be something as simple as tightening a screw or could be a more extensive repair or replacement.

Regardless, if this is your issue, you don’t want to wait to contact a technician. Loose parts could result in more costly repairs down the road.  

Buzzing Noise #3: Broken or Malfunctioning Fan Motor

Your outdoor AC unit houses a fan called the condenser fan. If your AC system is on, but the fan in the outdoor unit is broken or malfunctioning, the fan motor can cause the buzzing noise that you’re hearing. 

If this is your issue, you’ll need to enlist a professional to determine the issue and repair or replace the fan motor.  

Buzzing Noise #4: Frozen Evaporator Coils

If your AC has a refrigerant leak, it can cause part of your indoor AC unit, called evaporator coils, to freeze. Frozen evaporator coils can cause your system to make a buzzing noise. 

Other reasons your evaporator coil can freeze over include:

  • Restricted or reduced airflow
  • Dirty evaporator coils

Our first suggestion would be to check your air filter. 

Does it look like the filter on the right? If so, replace it and turn your AC system off for a few hours. Did the buzzing noise go away? If so, problem solved! 

If not, you may have low refrigerant or dirty evaporator coils, both of which will require a professional’s help. 

Ready for an AC repair? Hire NJ’s Best: Air Experts

If you are still having issues with your AC system, it’s probably time to contact a professional. With 25 years of experience serving NJ homeowners, you can rest assured that we will determine the repair needed and get your AC back up and running as quickly as possible.

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