Split AC Indoor Unit Making Noise: Comprehensive Guide 2023

Air conditioning units are essential for comfort during the hot summer months, but what should you do when your split AC indoor unit starts making noise? Fortunately, you can easily diagnose and resolve issues affecting your unit by following this comprehensive guide.

By the end of this article, you’ll have a better understanding of what’s causing the noise and how to fix it, ensuring a quieter and more comfortable environment in your home.

Understanding the Basics

Before delving into the specific issues causing noise in your split AC indoor unit, it’s important to gain a basic understanding of the unit itself.

What is a Split AC Unit?

A split AC system consists of two separate units, an outdoor unit, and an indoor unit. The outdoor unit houses the compressor, while the indoor unit contains the evaporator, air filter, and cooling fan.

Indoor Unit: Components and Functions

The indoor unit of a split AC system is made up of several components, each with a specific role to play. These include:

  • Evaporator coil
  • Air filter
  • Blower and cooling fan
  • Thermostat
  • Ductwork

Types of Noise

Different types of noise can be associated with a split AC indoor unit, and it’s essential to identify the specific type of noise to diagnose the problem correctly. Some of the common types of noise are:

  • Rattling noise
  • Squeaking noise
  • Whistling noise
  • Grinding noise

Specific Issues and Solutions – Split AC Indoor Unit Making Noise

1. Loose or Misaligned Parts

One of the primary culprits behind a noisy split AC indoor unit is loose or misaligned parts. Over time, the constant vibration of the unit can cause screws, bolts, or other components to become loose. This can result in rattling or vibrating sounds.

To resolve this issue, it’s essential to inspect the unit carefully. Tighten any loose screws or bolts using the appropriate tools. Additionally, make sure that the indoor unit is properly aligned and securely mounted to the wall or ceiling. This simple adjustment can significantly reduce the noise generated by loose parts.

2. Dirty Air Filters

Another common reason for a noisy split AC indoor unit is dirty or clogged air filters. When the filters are obstructed by dust, debris, or dirt, the airflow becomes restricted, causing the unit to work harder and produce more noise.

To solve this problem, locate the air filters in your split AC indoor unit. Gently remove them and check for dirt or debris accumulation. If the filters appear dirty, clean them using mild soap and water or replace them if necessary. Regularly cleaning or replacing the air filters not only helps reduce noise but also improves the overall performance and energy efficiency of your split AC.

3. Faulty Fan Motor or Blower Wheel

A faulty fan motor or blower wheel can also contribute to the noise emitted by your split AC indoor unit. If the motor bearings are worn out or the blower wheel is damaged, you may hear grinding, squeaking, or screeching noises.

If you suspect a problem with the fan motor or blower wheel, it’s best to contact a professional HVAC technician. They have the expertise and tools to diagnose the issue accurately and replace the faulty components if necessary. Attempting to repair or replace these parts on your own can be dangerous and may void any warranty on your split AC unit.

4. Refrigerant Leaks

Refrigerant leaks are another potential cause of noise in a split AC indoor unit. When refrigerant escapes from the system, it can create a hissing or bubbling sound. In addition to the noise, refrigerant leaks can also result in reduced cooling performance.

If you suspect a refrigerant leak, it’s crucial to seek professional assistance immediately. A certified HVAC technician will be able to locate and repair the leak, ensuring that your split AC operates efficiently and quietly.

5. Improper Installation

In some cases, the noise issue may be attributed to improper installation of the split AC indoor unit. If the unit was not installed correctly, it can cause vibrations and rattling sounds.

If you believe that the installation might be the root cause of the noise problem, contact a qualified HVAC technician to inspect and rectify any installation errors. They will ensure that the unit is properly installed, reducing noise and improving its overall performance.

6. Ductwork Issues

Issues with the ductwork can cause a rattling or whooshing sound in your split AC indoor unit. Check for loose connections, dents, or clogs in the ductwork and seal any leaks to solve the issue.

7. Thermostat Issues

A malfunctioning thermostat can cause your indoor unit to produce inconsistent or strange noises. You may need to replace the thermostat to solve the issue.

8. Electrical Issues

Issues with electrical components, such as loose wires, can cause a buzzing or humming sound in your indoor unit. Check for any loose connections and tighten them to solve the issue.

General Maintenance and Cleaning

Regular maintenance and cleaning of your split AC indoor unit can significantly minimize noise issues. Dust, dirt, and debris can accumulate inside the unit, leading to increased noise levels.

Make sure to schedule routine maintenance for your split AC, which typically includes cleaning the unit, lubricating moving parts, and inspecting for any potential issues. Additionally, keep the surrounding area clean and free from obstructions, as objects touching the unit can cause vibrations and generate noise.

Preventative Measures

To prevent issues that can lead to noise in split AC indoor units, it’s recommended to:

  • Regularly clean or replace air filters
  • Schedule routine maintenance checks
  • Avoid placing objects near the indoor unit

Regular Maintenance

Proper maintenance of your split AC indoor unit can help prevent issues that can lead to noise. Some maintenance tips include:

  • Cleaning air filters regularly
  • Cleaning the evaporator coil
  • Checking for any leaks in the refrigerant lines
  • Checking for any loose connections

AC Making Buzzing Noise Inside House

Indoor unit are vital part of split AC that help regulate the temperature in our homes. They ensure comfort and, in some cases, even save lives during scorching summers. However, malfunctioning air conditioners can cause issue of an AC making a buzzing noise inside the house.

The Buzzing Noise

The sound produced by an indoor unit of AC can vary depending on the problem. However, the buzzing noise is a common issue. The noise may come from the unit’s indoor component, ductwork, or even the outdoor unit. The buzzing noise inside the house could be due to a loose component, wiring issues, or debris in the AC’s fan section.

Loose Component

A buzzing sound from your AC might occur if the fan blades or motor have loosened. The vibrations from the loose components produce an irritating buzzing noise. Professional AC technicians can open and tighten these items, ensuring that they run smoothly.

Wiring Issues

Frail or damaged wiring within a unit can also trigger a buzzing noise. As electricity runs through the wiring, it may produce a buzz that is audible from inside the house. This issue should be addressed by professional technicians as it requires electrical knowledge and troubleshooting skills.

Debris in the Fan Section

Another common cause of buzzing noises inside the house is debris caught in the air conditioner’s fan section. Debris such as leaves, twigs, and dirt can hinder the fan blades from rotating correctly, and this produces an unpleasant buzzing sound.

Consequences of Ignoring Buzzing Sounds from AC

While a buzzing sound from your AC indoor unit may seem like a minor issue, it could indicate something significant that requires immediate attention. Failure to address buzzing noises could lead to the following consequences:

Reduced Efficiency

Buzzing sounds from your air conditioner can reduce the unit’s efficiency, leading to more energy consumption. This, in turn, could affect your energy bills.

Increased Risk of System Failure

Ignoring a buzzing noise from your air conditioner can cause more severe problems in the unit, leading to system failures. This can be costly to fix or even lead to the need for a replacement system.

Health Risks

A faulty air conditioner can cause health hazards such as respiratory problems, allergies, and more. Mold growth can result from excess moisture due to a malfunctioning air conditioner, leading to severe health problems.

Split AC Indoor Unit Making Noise When Off

If your split AC indoor unit is making noise even when it’s turned off, it can be quite perplexing. While it’s normal for the indoor unit to generate some noise while in operation, hearing noises when it’s supposed to be off can be a cause for concern. There could be a few reasons behind this issue.

One possibility is that residual refrigerant or pressure is causing the noise as it equalizes within the system. Another reason could be the expansion and contraction of the unit’s materials due to temperature changes.

Additionally, it’s possible that there is an electrical issue causing the unit to receive intermittent power and produce noise. If you’re experiencing this problem, it’s best to contact a professional HVAC technician to diagnose and address the underlying cause, ensuring a quieter and more peaceful environment when your split AC is switched off.

Inside AC Unit Making Rattling Noise


If you’re experiencing a rattling noise coming from inside your AC unit, it’s likely due to loose or misaligned components.

Over time, the constant vibration of the unit can cause screws, bolts, or other parts to become loose. When these loose parts rattle against each other or the surrounding casing, it creates a bothersome noise. To address this issue, carefully inspect your AC unit and tighten any loose screws or bolts using the appropriate tools.

Additionally, make sure that all components are properly aligned and securely fastened. By taking these simple steps, you can eliminate the rattling noise and restore a quieter operation to your AC unit.

Expert Opinion: HVAC Engineer’s Perspective

As an HVAC engineer with years of experience in the field, I’ve encountered numerous cases of split AC indoor units making noise. From my professional perspective, I suggest following these steps to address the noise problem:

First, check for loose or misaligned parts and tighten them accordingly. This is a quick fix that can resolve many noise issues.

Next, inspect and clean the air filters regularly. Dirty or clogged filters can significantly contribute to noise generation.

If the noise persists, it’s important to contact a qualified HVAC technician to diagnose and repair any faulty fan motors, blower wheels, or refrigerant leaks. They have the knowledge and expertise to handle these complex issues safely.

Finally, remember to schedule routine maintenance for your split AC unit to ensure optimal performance and minimize noise problems in the long run.

FAQs (Frequently Asked Questions)

1. Why is my split AC indoor unit making a clicking sound?

A clicking sound in a split AC indoor unit could indicate a problem with the electrical controls or relays. It’s best to consult a professional HVAC technician to diagnose and resolve the issue.

2. How often should I clean or replace the air filters in my split AC indoor unit?

It’s recommended to clean or replace the air filters in your split AC indoor unit every one to three months, depending on usage and the environment. This helps maintain optimal airflow and reduces noise.

3. Can I lubricate the fan motor of my split AC indoor unit to reduce noise?

No, it’s not recommended to lubricate the fan motor yourself. Consult a professional HVAC technician to handle any motor-related issues, as improper lubrication can cause further damage.

4. Is it normal for a split AC indoor unit to make some noise?

While a certain level of noise is normal, excessive or unusual sounds may indicate a problem. If you notice any new or unusual noises, it’s best to have your split AC indoor unit inspected by a professional technician.

5. How can I find a reliable HVAC technician to diagnose and fix the noise issue?

When searching for an HVAC technician, look for professionals who are licensed, insured, and experienced in handling split AC units. Ask for recommendations from friends or family, or check online reviews to find a reputable technician in your area.

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