Why is My AC Making a Loud Noise When Starting or Shutting Off?

Why is My AC Making a Loud Noise When Starting or Shutting Off?

AC Maintenance Services
Nowadays, AC device manufacturers implement technology and design, which helps in cooling effect without producing much noise. But, when you are getting some unusual sounds during turning on, and/or turning off your AC, it might be a major concern. So, the reason behind these noises can be due to a technical defect in the HVAC system or hardware problems. But, without getting in touch with certified experts and availing the
AC Repair services from them, the sound problem might not get resolved.

Also, it’s essential to be aware of the causes that can trigger sound problems while operating an AC appliance. Hence, if you are facing this issue and thinking “Why is my AC making a loud noise when starting or shutting off?” it’s time to consult professionals. By consulting them, you will be able to learn about some of the common sounds that AC devices or cooling appliances can produce. Moreover, they can also explain how you can stop these noises during switching on and off your AC device. 

Issues Causing Louder Noises in Air Conditioner Which Requires AC Maintenance Services

You can resolve the sound issue in your air conditioner using AC Repair solutions but, knowing the causes can prevent the headache. This is why you need to understand the main reasons behind strange sounds when the AC turns on/off. 

Slamming Air Filter Against Grill

Many consumers prefer to install the return vents in the ceiling area of their houses. So, the air filter is located in the grilles present inside these vents and further, connected to air duct as well. Now, whenever you switch on your AC machine, the air ducts start to suck in the air inside the room. But, there can be instances when the air filter can get stuck alongside the duct box as well. This is when the filter can hit against the grille during the time of switching off the air conditioner. It can often produce noise, which can be resolved only by getting in touch with AC Repair professionals. 

The experts will be able to check whether the air filters are damaged or having some other issues. The noise generated with this filter can also lead to producing a low-air quality. Hence, it is important that you let an expert inspect the situation and fix the source of noise from the AC device. 

Opening and Closing of AC Damper

If your AC appliance has a damper on it, you will be able to regulate the airflow amount through various parts of your home. This is when it can produce a slamming sound while closing the damper right after shutting down the air conditioner. Sometimes, this issue can take an extreme form and also might lead to many other problems. So, the best way to troubleshoot this problem is repairing the damper section. For this purpose, it’s best to get AC Maintenance services from technicians. 

Air Duct Expansion or Contraction

Often, the ducts made from sheet metals can be the reason behind producing creaking noises in AC. This can usually happen when the size of the duct is not proper and hence, air can’t pass through it. The noise generating from this unit is due to the temperature and pressure changes. This leads to contradicting and expanding the ducts and making strange sounds in AC. Now, if you want to resolve this issue, you can approach an agency that offers repairing services for air ducts and other components in AC. 

Fans in Air Handler or Indoor Unit

The segment inside your air conditioner consists of various components including the fan or cooling equipment. So, if any kind of malfunctions hit these units, the blower wheel in the machine tends to collide against the other parts. According to many AC users, they have found loosening of the fan’s mount. This can further lead to causing an imbalance in the components inside and can produce a loud noise. So, to fix this problem, you can call an expert for AC Maintenance and repair/replacement of the blower wheel. 

Compressor Having Broken Spring

Many experts have received complaints from users that they heard loud banging sounds during shutting off the AC condenser unit. This is basically the outside unit of the air conditioner, which has a compressor in it. The main purpose behind this unit is to pump the refrigerant in and out of the indoor AC unit. However, due to several reasons, the springs that support the compressor can break out easily. So, eventually, when you turn off the AC, the pump begins to lose the momentum. This is when it hit against the compressor’s case and produce a slamming or banging noise. 

So, the problem can be much complex than it sounds and might require an entire replacement of the compressor unit. If your air conditioner is within its warranty period, you can still replace it at a free or nominal cost. 

Types of Noises Generated by Air Conditioner Unit  and can be Resolved with AC Repair Services

You must never ignore unusual sounds coming from your AC device and cooling appliances. Any kind of noise indicates that something can be wrong inside your air conditioner unit. So, if you don’t fix the strange sound, it can transform the minor defects in your AC to a much bigger problem. But, before you call an expert, you need to be aware of the common sounds that can be produced in your HVAC system.


Getting a banging sound from your AC appliance clearly indicates that something is broken inside the unit. This can be anything including piston pin, crankshaft, connecting rod, which is present inside the compressor segment. It can also occur if one or multiple components in the indoor unit has some unbalanced or damaged parts. This is when experts always suggest to either replace the defective units or repair them. 


When some part inside your air conditioner is out-of-balance or loose, it can generate clanking noise. Sometimes, these components can have major failure issue and end up producing this sound frequently. Also, don’t ignore the loosening of your compressor unit, which is enough to create clanking noises. According to some users, they have noticed damages in the outdoor fan or indoor blower. This can further lead to this strange sound and create bigger issues in the AC unit. 


This sound usually comes from the outside unit of your air conditioner. But, this type of noise can also occur due to multiple issues in your AC equipment. First of all, if there are loose parts inside the compressor or main unit, you can hear a buzzing noise. Accumulation of debris in an indoor/outdoor section can also generate this strange noise. Also, if the fan motor or blades are unbalanced or loose, you can still get this buzzing sound. Hence, look for the condenser coil and copper lines, which can result in this noise due to rubbing against some other component. There are many customers who observed leakage in the refrigerant, which can freeze up the AC and cause this problem. 


If you observe clicking noise when your AC starts and shut down, there is nothing abnormal in this. But, the issue can be complex, if you get this sound constantly on a regular basis. As a result, this can be a major problem. The clicking sound generally occurs when the thermostat fails or the control unit gets defective. 

Now, when you hear this noise when the AC unit is running, there can be a blockage in the fan in the outdoor unit. However, getting this sound when the unit hasn’t started yet can be due to electrical problems. This is when you should contact the technicians to examine both the indoor as well as outdoor units in your AC. They are the right people to remove the obstruction from the outdoor unit’s fan. You can also ask them to repair the compressor, thermostat, or get the replacement for burnt circuit elements in the air conditioner. 


If you are getting this humming noise from your AC unit, it can occur due to loose components. Also, there can be problems in the refrigerant piping, which can point to a maintenance issue along with this sound. There can also be electrical problems and loose wiring, which can lead the air conditioners to generate humming noises. So, if you are hearing hums from the compressor or any other segment, you need to check if the motor is working perfectly. To get clarity on the exact situation, its best to get in touch with AC Maintenance professionals. 


The rattling, squealing and squeaking sounds usually comes from the fan and blower sections. It can get transmitted through your duct system, indicating the indoor blower motor and outdoor fan motor to have some technical issues. The squealing noise can also generate when the housing and blower wheel units get malfunctioned. But, to learn the actual cause of this kind of sound from your AC unit, you can take opinions from repairing professionals. 


When you switch on your AC device and it starts giving out high-pitched screaming or whistling sound, it can always be a critical issue. If it has caused because of a refrigerant leak, it can adversely affect the health of people in the room. The noise of screaming can occur due to a high level of internal pressure in the compressor unit. So, before this situation takes a dangerous turn, you can shut down your AC and call an expert. 

Apart from these common issues and noises, you might find various other problems and sounds in AC appliances. Sometimes, you can simply get a metal popping sound during the process of turning on or off your air conditioner. You can rely on their professionals to provide affordable and effective AC repair services. 

Frequently Asked Questions

1. How to Reduce the Noise in Your Air Conditioning Unit?

If the issue is not very critical so far, there are few methods to make your AC unit operate quietly. So, if the main reason behind louder noise in the air conditioner is the fan, you need to focus more on its cleanliness and maintenance. You must also carefully remove the debris from its blades or fix the loose ends. Sometimes, applying a little amount of lubrication also helps, when the motor doesn’t move smoothly and produce a grinding or humming sound in AC. You can also unclog the coil fins by removing the dust or dirt, which can make it noisy. 

2. What are the Techniques to Soundproof the AC Appliance from Outside?

If there is no specific technical error in your air conditioner unit and only the noise, you can try some simple tricks. Using these tips, you can easily soundproof your AC device. So, first, you can add an extra layer on your air conditioner by using an acoustic blanket on it. Otherwise, create a four-sided fence made from bamboo wood to cover the AC unit. You can also avoid the water dripping sound by making use of a bottle and hose to collect the liquid properly.