Humming Air Conditioner? Here’s What’s Going On

Humming Air Conditioner? Here's What's Going OnIt’s completely normal for an air conditioner to make a steady, low humming sound when it’s running. If the hum increases in volume, or becomes a loud buzzing noise, it’s often a telltale sign of a problem with a cooling system component that needs further investigation.

Common Reasons for a Humming Air Conditioner

If new or unusual buzzing noises develop, it’s wise to shut down the cooling system immediately and call your HVAC pro to find out what’s going on. Doing so is vital to protect your HVAC components from extensive damage and avoid situations that put your family’s safety at risk.

As a general guide, here are some frequent causes of loud A/C humming or buzzing:

  • Iced cooling coil. Under certain conditions, your evaporator coil can ice up and produce a humming noise. Once the system is shut down, make sure there’s a bucket under the coil to collect water as it defrosts, then, switch the power on again. If the coil freezes up again, your HVAC technician will need to diagnose why.
  • Seized fan motor. If the blower or condenser fan motor seizes up and needs replacement, but it’s still getting power, you may hear buzzing at your air handler or outdoor unit.
  • Faulty contactor relay switch. You can hear a loud hum from the outdoor unit if this low-voltage switch fails, which prevents the thermostat from signaling the unit to start up. Your technician can replace the switch to restore the flow of conditioned air, and it’s typically a fairly easy fix.
  • Loose wiring/electrical connections. A buzzing noise from any of your air conditioner’s electrical components is a sign of arcing, and this tells you there’s a risk of fire, so have it checked out promptly.
  • Bad circuit breaker. A faulty A/C breaker in your main electrical panel can produce a loud hum if the circuit is overloaded but the breaker doesn’t trip. If this occurs, there’s a significant danger of fire, so get it investigated without delay.

If you have concerns about a humming air conditioner in your Long Island home, contact us at Cool Power.

Our goal is to help educate our customers in Hauppauge, New York and the Long Island area about energy and home comfort issues (specific to HVAC systems). For more information about other HVAC topics, download our free Home Comfort Guide or call us at 631-292-0629.