Air Conditioner Sounds: Why Your A/C Is Making Noise & How to Fix It

How to Stop Loud A/C Noises When Starting Your Unit

Identify and Fix Problems in Your Unit
Read Time: 3.5 minutes
Sep 6, 2020

If your A/C unit is making clanging, screeching, or clicking noises when first turned on it is most likely a sign of damage within the HVAC system. If the noise occurs every time you turn on your unit and you can’t identify a cause, it may be time to contact an HVAC professional.

Keep in mind that if your unit makes noises during the entire duration of running it could be an indicator of another problem. In this article, we only cover A/C noises upon first starting your unit.

Loud AC Noises and What They Mean

It’s best to quickly identify the particular sound your A/C is making so you can attend to issues quickly and strengthen the lifespan of your unit.

Clanging and Banging

Man repairing ac unit

Loud banging from your unit each time you start it could be an indicator of debris within the unit. If it isn’t debris then it’s most likely a loose fan that is hitting against the HVAC cage. If you notice this sound from your unit, shut it off immediately. If you keep running the system it could result in further damage to your unit.

Cause: Debris in the unit
Fix: Remove obstruction or tighten fan back in place
Urgency: High


If your unit makes a screeching noise, like metal grinding against metal, it could be a sign that your fan motor bearings have broken. This isn’t a dangerously urgent problem but try to keep your unit off until you can get an HVAC technician to your house. If you keep running the unit it can end up causing more problems.

Cause: The fan motor bearings have been irreparably broken
Fix: Replacement of fan motor
Urgency: Moderate


Electrical problems are at play if your unit is making clicking sounds when you attempt to start the unit but never turns on. It is vital that you don’t try to fix this problem on your own.

Cause: Electrical problems – The thermostat, compressor, or capacitator could be broken in this case.
Fix: Call your HVAC technician. Don’t attempt to DIY an electrical problem fix.
Urgency: Moderate

Common Fixes for Loud A/C Units

AC condenser fan blades spinning

There are a few easy fixes you can follow through with routinely to cut back on obnoxious sounds coming from your A/C unit.

Clean and Straighten Coil Fins

Maintaining the coil fins on your unit can help improve efficiency. Try straightening coil fins with a fin comb and using a vacuum with a brush extension to clean up any lingering debris.

Tighten Loose Screws

Vibration while running can cause screws within your unit to loosen. This can cause rattling during operation but it can also eventually lead to parts coming loose within the unit. Have all loose screws tightened during routine maintenance calls or when trying to solve a noise problem.

Remove Debris Caught in Blades

Opening the A/C cabinet, locate the fan to search for any debris. Remove any debris you notice around the fan blades to eliminate banging and clanging noises coming from your unit upon startup. This is an easy fix that should only take a few minutes out of your day.

Straighten Bent Blades

While checking for debris, whether you do or do not find debris, you should check on the blades themselves. You can bend uneven blades back into place, but be sure to do so gently. You don’t want to inflict more damage on your unit by being careless.

After straightening the blades check the screws holding each blade in place. These should be tightened as you would any other screw on the unit. Screws become loose over time due to vibration and can result in more noise from your unit as it starts up.

Lubricate Motor

A screeching or grinding sound upon startup could indicate an unlubricated motor. Try lubricating the motor with SAE 10 oil. This should be applied to the oil ports in your unit which can be found in the small holes near the screws on the bottom of the fan motor.

3 Preventative Measures to Stop Future Problems From Starting

Technician checking air filter

Once you’ve dealt with the noise you’re probably not keen on dealing with it again. In order to prevent future HVAC damage, keep up with proper maintenance and install systems for your own comfort.

1. Install Noise-Reducing Barrier

Most units today operate below 55 decibels but if you have a particularly noisy unit you can opt for installing a noise-reducing barrier. You can use a noise-reducing fence, quiet fence, or sound blanket to cut back on the nuisance of noisy air conditioners.

2. Schedule Regular Inspections

Regular inspection can help to catch problems before they happen. An HVAC professional can identify any weaknesses within the system and suggest necessary repairs.

You should plan to have a maintenance inspection once to twice a year to keep your HVAC in good health.

3. Call in an Expert

If you suspect the beginnings of any problems within your system give your local HVAC expert a call. They can help you get your unit fixed before the problem develops into a full-blown catastrophe. In the long run, this can save you time and money.

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