Question: What does the noise from my AC unit mean?

May 10, 2018

Most of today’s high-efficiency AC units keep noise levels below 55 decibels.  So, if you hear an unusual or loud noise, don’t ignore it and turn a potentially minor issue into a major expense.  Below are the most common AC unit noises and what they may mean:

• Screaming – if you hear a high-pitched whistle or scream like noise, this could indicate a refrigerant leak in your unit or high internal pressure inside your compressor.  Both of these situations are dangerous for your family, shut the unit off and call a professional.
• Rattling – a rattling noise could mean that your unit is either starting to deteriorate, some of its parts are becoming loose like the fan, or that twigs or debris could be clogging it.  Check for loose screws and bolts in the unit, change the indoor air filter, and clean the condenser coils.
• Humming – if your compressor hums and refuses to start, more than likely there is an issue with your motor but first check the wiring as a loose wire would cause the same humming sound.
• Clicking – your AC unit will make a normal clicking sound as it starts up and shuts down but be aware if this clicking noise becomes constant,  it could indicate a defective control or failing thermostat.
• Banging – if you hear banging, something in your AC unit is not functioning properly and needs to be fixed right away before the problem causes more expensive ripple effects.  Banging indicates there’s a broken or loose part in your compressor system or that your indoor blower might be unbalanced.  Call a professional while there is still time to repair that one part and not have to replace the whole unit from the damage it caused!