Homeowners across Northern Kentucky and the Greater Cincinnati area are used to the quiet hum of their HVAC equipment as it operates. When sudden, loud HVAC noises are heard, your system is trying to tell you something! Oftentimes, loud noises from your heating and cooling equipment are cause for concern, so it’s important to know when to call for help.

For all of your HVAC system needs, contact the professional technicians at Rusk Heating and Cooling today.

Common HVAC Noises & Their Meaning

Loud noises coming from your HVAC system are typically signs of problems. In our most recent blog, the technicians at Rusk discuss what each noise may mean, what to do, and if repairs are needed.


Rattling noises from an exterior air conditioning or heat pump unit are often caused by debris inside the system. If you hear a rattling noise, shut off power to the system and take a look inside the outdoor unit. Remove any sticks, twigs, or other debris you find. If any components appear damaged, call your HVAC technician for repairs before using the system again.


A clanking sound often originates from the blower motor or its assembly. Loose components such as fan blades can make clanking sounds as the blower motor runs. If you hear these sounds, shut down your system and call for repairs.


Hissing noises mean there is air escaping from your heating, ventilation, and air conditioning system, which may point to a duct leak. You’ll likely hear this sound from within the walls, ceiling, or floor as air flows through the ducts. When this occurs, make sure to call your HVAC contractor for duct sealing to eliminate expensive air leaks.

Hissing can also be a sign of refrigerant leaks from an air conditioner or heat pump. A technician will need to find and repair the leak, then replenish the system with the proper amount of refrigerant.


Repeated clicking from the furnace when a heating cycle should start indicates a problem with your ignition system. This issue needs to be repaired right away to prevent further system issues.

Clicking at startup or shutdown is typically normal, as long as it doesn’t continue. If clicking sounds occur while the HVAC unit cycles, there may be an issue with the system’s electrical components that needs to be repaired.


A gentle hum as the system runs is normal. If the humming or vibrating sound is very loud, it can be a sign of loose parts or an out-of-balance motor. It can also be indicative of strain to the compressor or a failing motor. These abnormal humming sounds should be investigated by an HVAC professional as soon as possible.


Loud noises that sound like squealing or screeching are far from normal. They typically point to a blower motor belt that has broken, bringing the motor to a sudden stop. Continued squealing could be a sign of motor bearings that need lubrication – furnace maintenance typically takes care of this issue.


A booming noise that occurs as the furnace attempts to light is a sign of an ignition issue. If the ignition system struggles, gas can build up in the chamber. Once the system finally ignites, that extra gas is also ignited, producing the boom due to this small explosion. This is a safety issue, and you need to call for furnace repair immediately.


Whistling noises point to problems with your air conditioner or heat pump. The compressor may be acting up, in which case you want to shut the system down to prevent damage and call for help. Whistling may also indicate high refrigerant pressure, which requires professional repair.

Contact Rusk for Quality HVAC Repairs

Anytime you hear abnormally loud HVAC noises, call Rusk Heating and Cooling for repairs. Our technicians get to work quickly to diagnose and repair issues before they create more damage or dangerous conditions. When you need furnace, air conditioner, or heat pump repair services, contact us online or call us right away!