Is Your Air Conditioner Making a Humming Noise?

Do you hear your air conditioner making a humming noise? An AC hum is usually not a concern, unless the sound varies greatly from its typical sounds. 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.
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. 

Common Causes of Outside Air Conditioner Noise

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.

If Your Air Conditioner Make 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.

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