Anytime air conditioning noises don’t sound like the typical hum in the background, San Bernardino area homeowners need to take notice. Unusual sounds point to problems within the equipment, diminished performance and sometimes damage.

Different air conditioner noises clue you in to various potential problems. While the exact issue cannot be found for certain without a system inspection, some problematic noises tend to occur with a specific issue. Sanborn’s explains these noises and their causes below.


Grinding air conditioning  unit noises point to different system issues depending on where the sounds originate.

  • Grinding from the outdoor unit usually indicates a broken component or a part that has come loose inside the compressor. The pistons may also start to make a grinding noise, which means the compressor is wearing out. Both situations typically require compressor replacement. Repairing internal components on a compressor isn’t always feasible.
  • A grinding noise that comes from the indoor part of the cooling system is usually an indicator that the blower motor’s bearings have worn down. This can occur when the bearings do not receive lubrication through annual maintenance. In some situations, lubricating the bearings eliminates the sound; in others, bearings must be replaced.


A hissing noise can occur anywhere along the refrigerant lines and the components within the air handler and condenser unit that are connected. A refrigerant leak needs to be repaired right away or your air conditioner will be unable to function properly. If you have an older air conditioner that uses R-22 refrigerant (also called Freon), it is especially important to call an HVAC contractor right away, as this material is harmful to the environment. The source of the leak is found and repaired, then the system is refilled with the right level of refrigerant to allow proper cooling.

Hissing is sometimes paired with a high screaming air conditioner noise that comes from the outside unit. These air conditioner sounds warn of high pressure building inside the compressor. It is critical to shut the system off immediately and call for repairs. Sensors within the compressor may have malfunctioned, as well as the safety control that typically shuts air conditioners down in the event of high-pressure buildup.

Repetitive Slapping

If you hear a slapping noise that occurs on a somewhat regular interval, there may be an item caught between fan blades. If the noise comes from the outside unit, there could be something stuck down in the condenser hitting the fan blades, or a blade may have bent and is now striking another component as it rotates. When these air conditioning noises come from the air handler, there is likely something caught between the blades of the blower fan.


If you hear a clicking sound from either the indoor or outdoor cooling system equipment, a relay or control is probably bad. The noise may also come from a thermostat as it reads its last temperature readings. Relays and controls, including thermostats, typically must be replaced.

If the clicking air conditioning noises happen only when a cooling cycle begins and ends, this is a normal sound made by the system.

Sanborn’s Gets Rid of Air Conditioning Noises 

Don’t let those unusual air conditioning noises ruin your day in more ways than just the auditory disturbance – ignoring an unusual sound and keeping the air conditioner on can lead to more extensive system damage. Call Sanborn’s today to schedule air conditioning repair.