Jul 18

Air Conditioner Makes A Loud Noise When It Starts

image of homeowner covering ears due to air conditioner noises

It isn’t surprising when machines generate sounds. You can hear some level of noise around your home with the refrigerator, fans, and dishwasher running. Air conditioners also emit some noise. However, an air conditioner that makes a loud noise during startup isn’t normal. Investigate the reason when you hear anything unusual coming from your air conditioner. It may be signaling a bigger air conditioner problem. Read on to learn several causes why your air conditioner makes loud noise when starting and how to address it.

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Air Conditioner Makes Loud Noise When Starting

Air conditioners may emit loud noises when starting up. Listen closely as there are various kinds of noises. Each one is due to a different issue that needs to be resolved. Fixing them shouldn’t be a DIY project, and you should always contact an HVAC technician for help.

Types Of Air Conditioner Noises & Their Causes

image of a central air conditioner compressor

Read on to know more about the noises air conditioners make.

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Clanging & Banging Coming From The Air Conditioning Unit

The outdoor air conditioning unit has a blower motor to move air into your home. A damaged blower motor can result in unusual sounds. Components may also become loose and hit the cage. Other likely culprits are thermal expansion, fallen debris, and damper movement.

Screeching Air Conditioner

air conditioner condenser fan close up

You may have broken fan motor bearings if you hear what sounds like metal grinding against metal. This case isn’t an emergency, but you shouldn’t let the problem get worse. Contact your local, trusted HVAC technician to fix it before turning on your air conditioner.

Clicking Air Conditioner

Electrical issues typically cause clicking noises. You may try switching your air conditioner on, but it never actually turns on. Let professional HVAC contractors handle this problem. They will check your thermostat, compressor, and capacitor and repair what’s needed.

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Pulsating Cooling System

Expect low-level pulsating sounds from your system as air flows across it. However, this pulsating noise should only be heard from the outdoor unit and not the indoor one. If you hear it from your indoor air handler, there might be problems like broken fan blades or twigs in the unit.

Whirring Air Conditioner

This sound is due to an air conditioning mechanical problem. It can come from the outdoor and indoor units. Some of the usual culprits are faulty blades, blown fan motors, broken belts, and bad bearings. Switch off the unit right away and call an HVAC technician for repairs.

Buzzing or Humming Coming From Air Conditioner

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Check for any debris trapped inside the outdoor air conditioning unit if you hear an audible hum from it. Leaves, branches, and flowers may have slipped through the holes. Remove them right away. The fan may also be faulty if you hear a buzzing sound.

Rattling Air Conditioner

Rattling is usually because of loose air conditioner parts. The vibration may have caused them to loosen over time. Therefore, check the bolts and screws in the unit as they may need to be tightened. The coils may also need cleaning, and the filters changed. It is recommended that you call an HVAC technician and schedule air conditioner maintenance at least once a year.


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How An HVAC Contractor Repairs Loud Air Conditioning Units

Here are some of the usual air conditioning noise repairs:

Clean & Straighten Coil Fins

The coil fins should be cleaned to enhance efficiency and performance. Contact an HVAC technician and book yearly air conditioner maintenance. They will straighten the fin comb using coil fins and use a vacuum with a brush extension to remove all the dirt around the area.

Tighten Loose Air Conditioner Screws

image of an air conditioner technician tightening screws on ac unit

Air conditioners are made of numerous moving components, so it is normal for it to vibrate while running. This can also cause screws to loosen up after some time. If this happens, you will hear rattling every time your cooling system is on. Routine HVAC tune-ups ensure all screws are tightened.

Remove Debris on the Air Conditioner Blades

Get a better look inside by opening the AC cabinet. Remove any debris you see. Ensure that there are no foreign objects around the fan blades. This should be a quick and easy job that all homeowners can do.

Straighten Bent Blades

Check the blades after getting rid of dirt and debris. If it is uneven, they need to be bent back into shape. Contact an HVAC contractor if your air conditioner has bent blades. They will straighten it carefully to keep the issue from worsening. They will check each blade to return them back in shape.

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Lubricate Air Conditioner Motor

Poor motor lubrication can cause screeching sounds. Annual maintenance typically includes lubrication of the unit, so this problem doesn’t happen. HVAC professionals use the correct oil to eliminate the noise. They will also put oil in the oil ports near the fan motor’s bottom.

What A Homeowner Can Do If The Air Conditioner Produces A Loud Noise

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Listed below are several steps a homeowner can take when they hear unusual air conditioning noises.

Check the Outdoor Fan & Inspect the Unit

Check the condenser fan at the outdoor unit’s center first. If it rotates, determine how the blades spin. Debris in the casing can cause it to become off-balance or make sudden contact. Check the refrigerant piping and coils as well. Skip this step if you are unsure what to inspect. Leave this in the capable hands of a professional.

Change Your HVAC Air Filters

image of a dirty air conditioner filter that needs replacement

An air conditioner can’t operate properly with dirty air filters because air cannot flow properly. Therefore, it is an important task for all homeowners. Clogged air filters can cause the unit to struggle and make a humming sound. It is recommended that you check the air filters once a month and replace them as needed. Doing so makes your unit run more efficiently and improves your indoor air quality.

Clean Your Outdoor Air Conditioning Unit

The outdoor air conditioning unit is exposed to the elements in its immediate surrounding. Dirt and debris may have made their wait inside via the slits. For your safety, switch off the unit before opening the case. Take the top grille off and remove any fallen debris. Remember to close it back again.

Check the Run Capacitor

Switch the air conditioner on after cleaning it. Check if the fan is spinning. If it remains unmoving, try to jumpstart it using a long, thin stick. Push the blade to create momentum. If it starts spinning, you likely have a faulty run capacitor.

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Inspect Your Indoor Air Handler

The problem may not be with the outdoor unit at times. Check your indoor air handler after thoroughly checking the outdoor unit. There could be bent coil fins or ice accumulation. If it’s the latter, switch the unit off to defrost it. Let it dry before turning the unit on again.

Call an HVAC Company

Homeowners can help prevent air conditioner issues and stop common noise problems. However, untrained individuals can only do so much. Call an HVAC technician for professional assistance if you still hear some noise after doing the tasks listed above.


Preventive Measures for Air Conditioner Starting Problems

Install Noise-Reducing Barrier

Air conditioner noise can make it a challenge for you to focus on your day-to-day activities. It can even keep you up at night and ruin your sleeping pattern. Install a noise-reducing barrier to prevent this from happening. A noise-reducing fence or sound blanket is recommended for this purpose. Consult your HVAC contractor first.

Schedule Regular HVAC Maintenance

Book air conditioner maintenance once a year. Technicians can find the problems at their earliest stages with their trained eyes. They can provide quick solutions, so the problems don’t get worse. They will clean it thoroughly, so you don’t have to. This will reduce the chances of loud air conditioning noises developing.

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Call in an HVAC Expert

Contact a professional HVAC contractor at the first sign of odd air conditioner noises. Don’t neglect them so that they don’t turn into even worse problems. It is always more affordable to repair minor air conditioning problems than find solutions for full-blown failures.



Be attentive to your air conditioner. If you care to listen, your cooling system will tell you when it is malfunctioning. Keep in mind that manufacturers try their best to reduce the noise an air conditioner makes. You can determine what’s normal with your unit after observing it. Anything that might seem off needs to be investigated immediately. Ask help from a competent professional HVAC technician for advanced repairs.

Call Skylands Energy Service For All Of Your HVAC Requirements

image of skylands energy service logoCall Skylands Energy Service when you need superior HVAC services in Central New Jersey. Our company has the best professionally certified technicians for all your heating and cooling needs, including maintenance, replacements, repairs, and installations. All our friendly techs can service any HVAC system correctly using the right tools, knowledge, and extensive experience.

Look no further than Skylands Energy Service for the most competitive HVAC service rates in the area. Our tune-up services help you achieve higher energy efficiency and better home comfort while reducing your energy costs. We can recommend the best HVAC repair or replacement system that is within your budget. All our work is guaranteed to ensure your satisfaction. Call Skylands Energy Service today to schedule a service appointment. We offer free, in-home estimates.

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