Is Your Air Conditioner Making a Humming Noise?

Updated August 20. 2024

Can you hear a consistent humming noise coming from your AC unit or outdoor HVAC unit?In many cases an AC humming noise is not a concern, however if the sound varies greatly from its typical sounds there could be a more serious issue with your HVAC system. Don’t worry, if the HVAC is making a buzzing noise you’re not alone. In fact, this is one of the most common noises central air conditioners make. Sometimes the hum is louder at different times and sometimes the hum noise level is more intense with different AC brands. Learn more about what causes this noise, how to troubleshoot if it could be stemming from a problem with your AC, and what to do if it is.

What Causes Air Conditioners to Make a Humming Noise

A hum usually indicates the steady drive of the outside fan blade and motor, but a humming or buzzing sound could also indicate a mechanical or electrical issue.

The heavy equipment making up a central air conditioning units can be expected to make occasional hisses, pops, rattles, and the like. When you hear persistent humming and buzzing, though, you may have a problem that calls for professional HVAC repair. If this is the case, don’t hesitate to reach out to the team at Howard Air for professional help.

If Your Air Conditioner Makes a Loud Hum, Check the Following

Here’s what to check if your HVAC system is making an unfamiliar sound.

1. Condenser fan motor:

The HVAC’s fan motor could be seized (unable to spin) but power is still going to it, creating resistance that produces a loud and noticeable hum.

2. Contactor relay switch:

Inside your outside unit, the air conditioning contactor serves to turn on the outside unit when the house temperature rises to the level where cooling is required. This contactor can fail mechanically or electrically, and will produce an electrical murmuring sound at failure.

Why is My HVAC Unit Making a Loud Humming Noise?

Here are some root causes of your cooling system’s hum.

1. Loose wiring:

When electrical wires separate by just a little, an electrical arc can be created, which can produce a buzzing sound and the potential for an electrical fire.

2. Circuit breakers:

An overloaded circuit breaker can buzz if it is faulty and unable to trip, or your breaker panel can buzz from normal electrical flow. Get a qualified HVAC contractor to check it.

3. Condenser fan motor:

Yes, it could hum (see above), but it can also buzz from resistance from the failed motor. Without the fan motor turning the fan, your home will not cool down efficiently.

Get Expert Help With AC / HVAC Humming Noises in Phoenix

For air conditioner repair, Phoenix homeowners are wise to call professional HVAC contractors to diagnose and repair noises. Electricity is dangerous; the circulating refrigerant in your home’s AC is also strong stuff that requires expertise.

Most homeowners lack the proper training to diagnose or repair an air conditioning system and considering the investment you placed in it, you cannot afford to risk further damage. We encourage you to contact Howard Air at (602) 953-2766, rather than attempt a repair yourself, if you hear rattling, grumbling, or clattering sounds coming from your air conditioner.