Why Is My AC Making Noise? 7 Reasons You Have a Loud AC
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Why Is My AC Making Noise? 7 Reasons You Have a Loud AC


A noisy air conditioner can be both irritating and worrisome. While many things can cause your AC to make noise, pinpointing the exact cause will help you determine if the sound is harmless or a sign of a larger problem.

If your AC is making loud banging, hissing, or high-pitched squealing sounds, contact a trusted HVAC company as soon as possible for repairs. These noises often mean you have a serious problem that needs immediate attention.

Below, we’ve compiled some of the most common noises you’ll hear coming from your air conditioner and what they mean.

  1. AC Makes Rattling Noise

A rattling sound coming from your AC can indicate a few different things. There may be a loose screw or one of the fan blades may be bent or misaligned. Alternatively, there may be loose debris inside your outdoor AC unit.

If you feel comfortable taking on the task, open the air handler cabinet, vacuum out any loose debris from around the fan, and clean the blades. If the fan blades seem loose, tighten the hub using an Allen wrench or screwdriver. Then, examine the blades and if any appear bent, apply gentle pressure to straighten them out. Finally, tighten up the loose screws with a screwdriver. If these simple fixes don’t solve the problem, call in an HVAC expert for help.

  1. AC Making Grinding Noise

A grinding noise coming from your AC is often a sign that the motor needs lubrication. If your unit has oil ports, you can lubricate it by adding a couple of drops of SAE 10 oil to each one. To prevent these noises from returning, make a habit of oiling the motor at the start of each cooling season.

Unfortunately, a grinding noise can also signal that your AC compressor is worn out. If this is the case, you may need to replace your compressor or your AC unit entirely.

  1. Air Conditioner Makes Humming Noise

A humming noise usually indicates there’s a problem with your AC’s contactor relay switch. This switch is the communication point between your thermostat and your outdoor unit. When this switch breaks down, your AC will stop being able to function properly. Because the relay switch is connected to the unit’s electrical system, you’ll need to get this checked out by a licensed HVAC technician.

  1. AC Unit Making a Buzzing Noise

Your outdoor unit can start to get noisy when debris accumulates on the coil. To clean out the coil, gently hose it down with a garden hose. If it’s still making noise, check to see if the aluminum fins look bent.

If they do, straightening them may help reduce the noise. To straighten the fins, you’ll need to use a fin comb, which can be bought at your local hardware store.

  1. Air Conditioner Sounds Like a Helicopter

If your air conditioner is making a whirring noise that sounds like a helicopter, you may have a problem with your AC’s blower fan motor. The ball bearings may have come loose or the fan may be coming apart in some way. Unless you have HVAC experience, it’s best to have this problem addressed by a professional.

  1. AC Making a Clicking Noise

It’s typical to hear a clicking noise coming from your air conditioner when you first turn it on or shut it off. But if you’re hearing a clicking noise constantly during operation, something else may be wrong. In most cases, a clicking noise signals that something is wrong with your AC’s electrical system. Electrical issues should always be handled by a trained HVAC specialist.

  1. AC Making a Hissing Noise

If you hear hissing, whistling, or shrieking coming from your AC, turn your AC system off immediately and call a professional HVAC technician for help. These noises can indicate that there is pressure building within your unit, which can become quite dangerous if left unaddressed.

Schedule Tigard AC Repair Service

For an expert diagnosis of what’s causing your noisy air conditioner, contact the team at Roth Heating & Cooling, Plumbing, Electrical, Drain Services.

We handle everything from air filter changes to refrigerant leaks, worn-out compressors, broken blower motors, and more! We’re the trusted choice for AC repair in Tigard, OR, and we’ve been helping homeowners stay cool and comfortable for over 45 years!

Call us today at 503-266-1249 to schedule service.

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