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Sierra Pacific Home & Comfort, Inc. Blog

AC Noises to Never Ignore

woman-covering-ears-on-white-backgroundIt would be nice if we had air conditioners that could self-diagnose malfunctions and report them back to the homeowners in detail, right? Honestly, that’s probably not too far-fetched of an idea when you really think about it.

In the meantime, though? This isn’t a reality and we need to rely on other methods for our air conditioner to send warning signs that something is amiss. This may be a drop in cooling power, or an unexpected and unexplained spike in energy bills. Or, it may be that your circuit breakers for the indoor and outdoor units keep tripping.

Or, it could be noise. “Wait,” you might be thinking, “my air conditioner always makes noise!” We aren’t talking about the hum of the fans or the faint clicking you might here when the system starts up and shuts down, though. Rather, we’re talking about sounds that are abnormal to what you normally hear, or seem louder than they should be. What could this include? Read on!


We’re referring to a loud, mechanical noise—it’s most commonly an indication of a motor problem, or at least the sign of a motor bearing that has worn down (this isn’t inherently uncommon or bad, but it should be repaired ASAP).

A worn-down bearing eventually creates too much friction for the motor, and can permanently damage it. Our technicians can quickly and accurately replace these bearing in order to save your motor and prevent further damage.


A grinding noise is also a sign of a motor problem. It’s usually caused by a motor that has accumulated too much dust and debris, or has lost too much lubrication over time. Again, this is a natural part of wear and tear—and something we check during AC maintenance—but it should definitely not be ignored.

If you smell an acrid stench coming from your vents in combination with the grinding noise, it’s a sign that your motor is already overheating. Please turn your AC off right away in this case, and give our pros a call.


Rattling can be a minor “problem,” nothing more than a sign that a cabinet door is loose. This is something you can fix on your own, typically, with a few twists of a screwdriver.

However, it could be the sign of something else—loose components being knocked around in your blower fan or bent fan blades. It may even be that your air conditioner’s cabinet is coming loose from the slab, or you have ductwork damage. When and if in doubt, please don’t hesitate to give our pros a call.


No, we’re not talking about the sound an angry cat makes … but more like the sound air makes escaping out of a tire or an air mattress. What’s probably happening when you hear this noise is that refrigerant gas is escaping out due to damage to the line. Refrigerant is essential to AC operation, so it’s something you want inspected and repaired right away.

This can also present itself as a bubbling noise if it’s refrigerant leaking out in liquid form.

When you need reliable air conditioning service in Sacramento, just look for The Guys in the Big Red Trucks! Contact Sierra Pacific Home & Comfort, Inc.

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