Air Conditioning / August 24, 2021

Factors That Determine HVAC Noise Levels

Some noise is inevitable when your air conditioner runs. However, a good AC shouldn’t be so noisy that it interferes with your home comfort or work. You can determine how quietly your AC will run right from the installation stage. Below are the relevant factors that determine AC noise.


Some HVAC models are relatively quieter than others. HVAC systems have decibel ratings that indicate how quiet they are. The decibel (dB) is the unit for measuring noise levels. The lower the dB, the quieter the HVAC is.

Ratings within the 50 to 60 dB range are good enough for the outdoor units. Aim for 20 dB for an indoor unit. For comparison, 70 dB is what a typical vacuum cleaner sounds like when it runs.

Type of Fan

The HVAC system’s moving parts are responsible for most of the noise the system generates. Since the fan is one of the major moving parts, it’s responsible for a sizable percentage of the noise. Thus, looking for a relatively quiet fan will give you a relatively silent HVAC system.

For example, some HVACs have variable speed fans that run at different speeds depending on the needed heating or cooling levels. Such HVAC systems run relatively quieter than others that always have to run at full speed. Some HVACs also have noise-reducing fan blades whose designs don’t produce as much noise as other fans, even when running at the same speed.

Fan Setting

Apart from type, fan settings also determine noise levels. Many HVAC systems have two fan settings – “On” and “Auto.” The “On” setting makes the fan run during both the “On” and “Off” cycles of the HVAC. The “Auto” setting only produces forced air circulation when you need active cooling or heating – the fan stops running during the HVAC’s “Off” cycle.

Using the “On” setting makes the HVAC noisier since the fan will always run. The “Auto” setting reduces the noise since the fan stops running for each half of the HVAC cycle.

Installation Location

Sound waves weaken over distance. Thus, the farther away your HVAC system is, the quieter it will seem to you. The distance issue is one reason window ACs seem louder than other HVAC units – the window unit must be in the room to work. Similarly, an HVAC outside unit right next to the exterior wall will be louder than a similar unit farther from the wall.

The materials between you and the outside HVAC unit also determines how much noise will reach you. For example, placing the unit right next to a window allows much more noise to get into the house.


A well-maintained system will run quieter than a poorly maintained one. Poor maintenance:

  • Leads to a blocked air filter that forces the system to work harder than it should and make more noise
  • Leads to loose or damaged parts that rattle as the system runs
  • Leads to inadequate lubrication of moving parts that increase friction and noise

HVAC systems also tend to get louder with time due to the accumulation of wear and tear effects.

Mauzy Heating, Air & Solar has over 52 years of experience in the heating and cooling industry. We can help you install, maintain, and repair your AC to avoid malfunctions – including malfunctions that can make the system too noisy. Contact us for a quote on all your HVAC needs.

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