Modern high-efficiency AC units use quiet two-stage compressors and sound dampening to keep noise levels down. That means when you start to hear loud noises, something is wrong. Remedies range from maintenance (like air duct cleaning) and tune-ups to expensive repair jobs, to complete replacement and new AC installation.

These are some of the most common noises our technicians get called to provide HVAC repair services for:

  • Banging: A part has likely become loose or broken off inside the compressor. This is often a critical component such as a piston pin, connecting rod, or the crankshaft, but it might also indicate the blower is off balance.
  • Buzzing: Is most often heard near the air handler in your home or near the outdoor unit. Buzzing usually arises from an electrical problem, which may originate from a motor, capacitor, compressor, or a loose wire. However, loose parts and debris can cause a buzzing noise as well.
  • Clicking: A constant clicking sound can mean the thermostat is failing or there’s a problem with the control system. If the AC clicks but doesn’t start, there’s likely an equipment problem. Clicking as it’s running can mean a foreign object has entered the blower fan.
  • Squealing: A squealing or screeching sound, as if metal is grinding against metal, often signals a problem with the compressor, outdoor fan motor, or blower motor. The sound can travel throughout the duct system, so it might be heard far from the affected component.
  • Whirring: Helicopter-like sounds typically mean there is a mechanical problem, such as worn bearings in the blower fan motor or loose or broken fan blades. There could also be a bad belt or debris trapped in the system.

Possible Reasons

If your HVAC system is making noises, an air conditioning technician may look into the following reasons:

  • Refrigerant Leak: A high-pitched whistling or screaming sound is usually caused by a refrigerant leak. But it can also mean the pressure inside the compressor is very high. Either situation is very dangerous, so call a technician right away.
  • Slipped Belt: The squealing sound of a slipped belt is quite distinct. Connecting the compressor to an engine, the belt will start to squeal just before breaking, at which point your AC will shut down.
  • Loose Parts: Loose components inside your HVAC system, such as screws or other small parts, tend to make lots of noise. The louder the rattling, the looser the part and more likely it is to cause more damage.
  • Failing Motor: A bad motor can put your entire AC system at risk. You’ll likely need fan motor repair if you hear a humming noise, which can also mean the capacitor can fail and starve your AC of energy.
  • Electrical Issue: An electrical malfunction can occur due to an incorrect voltage supplying the system, which can cause a breakdown, or a loose connection with the compressor or other component.
  • Duct Leak: The sound of air leaking from a duct also translates to a loss of energy and money. If you hear a whistle from your AC ducts, have it checked by a professional who can fix the problem.
  • Faulty Compressor: A failing compressor can be quite loud. There’s no way to repair a compressor, as it’s hermetically sealed, meaning trying to open the case will cause irreparable damage. Usually, the most cost-effective solution is to replace the entire AC unit.
  • Normal Wear and Tear/Old System: The typical wear of mechanical and electrical components eventually takes a toll. If your unit is over a decade old and has major repair issues, consider replacing it with a more efficient system.

Contact Black Hills Inc. Home Services

If your AC is making noise, the licensed technicians at Black Hills can pinpoint the reason and make the necessary repairs. Our team is skilled at AC and furnace repair as well as servicing the latest types of heat pumps. To learn more about our HVAC repair services or schedule an appointment, request service online or call 888-978-2917.