Air Conditioner Makes Loud Noise When Starting

young homeowner covering ears due to loud noises from air conditioning unit when starting

It’s never a real surprise when machines make noise. No home is ever completely quiet because modern homes have fans, refrigerators, dishwashers, dryers, or washing machines running. Even an air conditioner unit will emit a slight sound. However, it should not be considered normal for your air conditioner makes loud noise when starting. If you hear something out of the norm, it’s a good plan to investigate the source because it just may be a symptom of a real air conditioner problem. Let’s look into possible causes and solutions if you have noticed your air conditioning unit getting louder.

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Air Conditioner Makes Loud Noise When Starting

Homeowners often hear loud sounds when their air conditioner is starting on a hot summer day. Listen closely to them, because there are distinctive types of noises and each of them points toward a unique issue that needs to be addressed. Do not try to fix it yourself. Reach for the phone and look for an experienced HVAC technician to help.

Different Air Conditioner Noises & What Causes Them

image of an AC compressor unit that is making a banging noise

Read on for more info about unusual air conditioner unit noises.

1. Clanging or Banging Air Conditioner Sounds

Each air conditioner’s outdoor unit will contain a blower motor. This is what moves air into the home. If this part of your unit is damaged, it could begin to make odd noises. Parts may also have moved out of place and may even be hitting the air conditioner cage. Fallen debris or thermal expansion, as well as damper movement, may possibly be suspects, too.

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2. Screeching Air Conditioner Sounds

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If it sounds like metal is grinding somewhere against another piece of metal, you could have broken bearings in the air conditioner fan motor. It may not be an emergency situation, but it is wise to do something about it so you can prevent it from getting any worse. Call an HVAC technician and ask them to come over to fix the problem before you use the air conditioner again.

3. Clicking Sounds in Your Air Conditioner

When your air conditioner is emitting clicking sounds, it often indicates that you have air conditioner electrical issues. You perhaps attempted to start the air conditioner up, but the unit did not turn on. This problem should be put in the hands of a professional HVAC contractor. They are likely going to focus on the capacitor, the air conditioner compressor, or the thermostat.

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4. Pulsating Cooling System

A lower-level pulsing sound is expected as air flows in the cooling system. However, if there is a pulsating noise from the outdoor air conditioner unit, it should not be able to be heard indoors. If you can hear it, you might have a problem like twigs or even broken fan blades inside the cooling unit.

5. Whirring Sounds in Your Air Conditioner

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This sound is likely going to point to mechanical issues within the air conditioning unit. It may even come from both the indoor unit and the outdoor one too. Common causes are broken belts or faulty air conditioner blades. It could also be bad bearings, or a blown motor in a fan. You should turn the unit off immediately and call a tech for air conditioner repair in this instance.

6. Buzzing or Humming Noises Coming From An Air Conditioner

If you’re hearing your outdoor air conditioning unit humming loudly, check for debris trapped in it. Sometimes, flowers or leaves and branches slip through the holes. Removing any debris should help. A buzzing sound could also be an indicator that the fan in the unit is going bad.

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7. A Rattling Air Conditioner

Rattling sounds are often due to air conditioner parts that have worked loose from vibration. Check all of the screws and any bolts in and around the unit. They may just need tightening. It’s also wise to clean off the coils and put in a new air filter after. An even better plan is to call an HVAC company to schedule an annual air conditioner cleaning and maintenance visit.


Some Common HVAC Contractor Repairs for Noisy Air Conditioning Units

1. Clean and Straighten Out the Air Conditioner Coil Fins

Be sure to keep the coil fins clean, as this will improve performance and efficiency. Reach out to an HVAC contractor to schedule that annual air conditioner tune-up. During this HVAC  appointment, they will use a fin comb and straighten out the coil fins. They will also use a vacuum and brush extension so they can get all the dirt cleared out from around the area.

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2. Tighten Up Loose Air Conditioner Screws

With so many moving components, air conditioners are going to vibrate while they are running. This can cause screws to become loose after a while. It can reach a point where the rattling sounds are heard every time it’s running. Scheduling routine HVAC maintenance will help with this issue, as the tech will check these yearly.

3. Remove Debris from the Air Conditioner Blades


air conditioner compressor fans

Opening up the air conditioning cabinet will allow you to get a better look inside it. If there is debris, remove it right away. Pay close attention to foreign objects near the fan blades. This is a quick, easy task that any homeowner should be able to do.

4. Straighten Out Bent Blades

After removing any dirt or debris, check the blades carefully for any issues with them. Uneven blades need to be bent gently back into shape. Call the HVAC contractor if you notice blades that were bent. They can straighten them to prevent matters from growing worse. A tech can systematically go over each blade until everything is in good working order.

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5. Lubricate the Air Conditioner Motor

Screeching sounds may be pointing to poor lubrication within the motor of the unit. Lubrication is done during an air conditioning tune-up service, which will help to prevent this issue from occurring, to begin with, and repair it if needed. The technician will use the correct kind of oil to eliminate the noise. In addition, they can add oil to the ports located near the bottom of the fan’s motor.

What Can A Homeowner Do When An Air Conditioner Makes Loud Noises

Below are tips on what a homeowner can do if they experience any unusual air conditioning unit noises.

1. Inspect the Outdoor Air Conditioner Fan & Unit

First, look at the condenser fan that’s at the center of an outdoor unit. If it rotates, check carefully to see how the blades spin. Signs of them being off-balance may be caused by debris within the casing. Look over the coils and inspect the refrigerant piping, too. If you aren’t sure of what you are seeing, you may want to skip this step and just leave it to a professional.

2. Change All HVAC Air Filters

image of a dirty hvac filter

This is a necessary task for homeowners to perform regularly. Your air conditioner unit is not going to run well if its filters are clogged and dirty. Airflow will suffer. The unit will be struggling to run and might be emitting a humming sound. Be sure to check air filters monthly when the AC is in use. Replace them when it’s necessary.

3. Clean the Outdoor Air Conditioner Parts

An outdoor unit is exposed to the elements in the environment around it, so dirt and debris often make their way in through the casing. For safety’s sake make sure you turn off the unit before you ever open up the case. Remove the grill on top and clear out any fallen objects. Be sure to carefully close it up again when finished.

4. Check on the Run Capacitor

After you have cleaned out the unit, turn your air conditioner unit back on again to see how the fan is spinning. If it doesn’t move freely, you can attempt to jumpstart it by using a stick or another long object to push on the blade to create some momentum. If the blades begin to spin, you likely have a faulty run capacitor.

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5. Inspect the Indoor Air Handler

There are times when the problem isn’t with your outdoor AC unit. Once you complete that inspection, you can move to the indoor air handler next. Look for any ice build-up and see if there are bent coil fins. Be sure you turn off the power to allow it to thaw. Also, make sure you let it dry fully before you turn it on again.

6. Reach out to an HVAC Company

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Homeowners can many different things to prevent air conditioner issues and stop common noises in their units. However, there are limits to what an untrained person will be able to do. If you still hear odd noises after doing all of the recommendations on this page, it’s time to call in an HVAC professional.

Preventive Measures with Air Conditioner Start-Up Problems

1. Installing a Noise-Reducing Barrier

Air conditioner noises may be loud enough to inhibit focusing on your daily tasks. Sounds from your unit can also keep you up at night and wreak havoc on your sleep. Prevent this from happening by installing a barrier that will reduce noise. Using a sound blanket or installing a noise-reducing fence is ideal for this but talk to a qualified HVAC contractor before choosing one.

2. Schedule Regularly Occurring HVAC Maintenance

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Schedule yearly air conditioner maintenance calls for your AC unit. With a trained eye, a licensed technician will be able to spot problems early. They will then intervene with quick solutions to prevent any issues from getting worse. A technician can conduct a thorough unit cleaning to help lower the possibility of any loud AC noises developing in the first place. Maintenance is always better than repair.

3. Call on an HVAC Expert

Look for an HVAC contractor if you hear any unusual air conditioner noises coming from your unit. You cannot ignore these, as they will likely soon evolve into something that may be far worse. It is generally more affordable to fix any minor cooling system issue than to look at remedies for a full-blown unit failure.

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To Conclude

Be sure to pay careful attention to your air conditioner unit as it can tell you in subtle ways if something is going wrong. Manufacturers build them to minimize noise and you can often get a good feel for what is normal or not by listening to and looking after your AC unit. If something seems to be off, you should investigate as quickly as you can. Seeking help from competent professional technicians is wise if you suspect it may need any advanced repairs.

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Lawes Company provides advanced heating as well as cooling service for residents of Monmouth and Ocean Counties, New Jersey. This company only hires the best. You are assured of a certified technician who is able to provide excellence in HVAC tune-ups, timely repairs, professional installation, and the correct replacement if needed. All of our techs have the knowledge as well as the experience to service HVAC systems correctly.

Lawes Company guarantees competitive heating and cooling costs to keep your summer comfortable. Our maintenance service is sure to improve your comfort, increase energy efficiency and reduce home heating and cooling expense. If you need an HVAC repair or a replacement system, let us recommend the best solution for your home. We will work with you to get you the best system within your budget. Our company backs every bit of our work with a guarantee of your satisfaction. If you are ready to schedule an appointment, just pick up your phone and give Lawes Company a call. Ask us about our free, in-home repair or an HVAC replacement estimate.

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