Why Your Air Conditioner is Humming but Not Running?

Last Updated on May 4, 2023 by Kimberly Crawford

If your air conditioner is humming but not running, you may be facing an issue that needs to be addressed quickly.

This guide will provide a brief overview of the potential causes and solutions for this issue, so you can get your air conditioner working again with minimal disruption.

Knowing what could be causing the problem and how to troubleshoot it can help you save time and money. So, let’s get started!

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Symptoms of Air Conditioner Humming but Not Running

air conditioner humming

Inconsistent or no cold air

This issue could be caused by a problem with the compressor, blower motor, or refrigerant levels in your system. To diagnose the cause of the problem, you will need to check for signs of wear and tear on these components.

If possible, do a visual inspection to look for any debris or other visible obstructions that may be blocking the air flow.

If the issue is related to a lack of refrigerant, you will need to contact a certified technician who can inspect your system and add additional coolant as needed.

Unable to power on the unit

This could indicate an issue with the electrical components in your system, such as a blown fuse, tripped breaker, or worn wiring.

To diagnose the cause of the issue, you will need to check your electrical panel and power source for any signs of damage.

If there is an issue with the wiring in your unit, it’s best to contact a professional who can safely and correctly repair or replace any damaged components.

Unusual sounds

This could be caused by an obstruction in the air flow or a malfunctioning fan motor, blower motor, or compressor.

To diagnose the issue, you will need to carefully inspect each component for signs of wear and tear. If possible, you should also check for any obstructions that may be blocking the air flow.

If you find any visible damage, you should contact a certified technician to inspect your system and safely repair or replace any damaged components.

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Potential Causes and Troubleshooting Steps

Capacitor malfunction

1. Symptoms of capacitor issues include reduced airflow, weak or no cooling, and humming but not running.

2. To test and replace the capacitor, you will need to use a voltmeter to check the voltage running through it. Make sure you have turned off the power before touching any electrical components. If the capacitor needs to be replaced, make sure you find one with the same voltage and microfarad ratings as the one you are replacing.

3. To ensure proper capacitor installation, use insulated electrical tape to cover any exposed wires and make sure all connections are secure. Also, check that any wiring is not crossed or touching each other.

Electrical connection problems

1. Signs of electrical connection issues include inconsistent or no cooling, and humming but not running.

2. To diagnose the issue, you will need to turn off the power at your circuit breaker panel and inspect all connections for signs of damage or corrosion. If any components appear to be damaged, you should contact a certified technician to repair or replace them.

3. Once all connections are secured, you can check the air conditioner’s power connections for any signs of damage or exposed wires. If any loose wires are found, ensure that they are properly connected and covered with electrical tape to prevent any possible hazard.

4. If you find any damaged wires, they will need to be replaced. Make sure you select a wire of the same size and insulation rating as the one you are replacing.

Motor issues

1. Indications of motor complications include humming but not running, screeching noises, or a burning smell coming from the unit.

2. To test the motor for functionality, use a multimeter to check the voltage running through it. If there is no reading or power running through the motor, it will need to be replaced or repaired.

3. If you decide to replace the motor, make sure you select one with the same voltage and horsepower rating as your old motor. Also, make sure that the shaft is correctly aligned to ensure proper functionality.

Loose or damaged components

1. Detecting loose parts can be done by inspecting the tubing and vents for any signs of movement or detachment. If any components appear to be loose, make sure you tighten them securely.

2. If any parts are found to be damaged, they will need to be replaced. Make sure you select components of the same size and material as the ones being replaced.

3. After all loose parts have been tightened, inspect all other components for signs of damage or wear and tear. Any damaged components should be replaced immediately with ones of the same size and material.

Frozen evaporator coils

1. Recognizing frozen evaporator coil symptoms can be done by inspecting for frost or ice build-up on the interior panels of your AC unit. If these signs are present, it is likely that the evaporator coils have become frozen.

2. To thaw the frozen coils, turn off your AC unit and wait for the ice to melt before turning it back on. Make sure you check all connections for any loose wires or components that may have caused the problem in the first place.

3. To prevent evaporator coil freezing in the future, make sure you keep your air filter clean and replace it on a regular basis. Also, check that your AC unit is set to the correct temperature settings and that all components are installed correctly.

4. If you continue to experience frozen evaporator coils, contact a certified technician to inspect your air conditioner for any underlying issues. They may need to replace or repair certain components in order to get your AC unit functioning properly again.

Refrigerant Leaks

1. Signs of a refrigerant leak include warm air coming from the vents, icy or frosty buildup on the evaporator coil, and inconsistent cooling.

2. To diagnose a refrigerant leak, you can use an electronic leak detector to identify any possible leaks. If a leak is found, contact a certified technician immediately to repair or replace it.

3. Once the leak has been repaired or replaced, your technician will need to recharge the system with the correct amount of refrigerant in order for your air conditioner to operate properly.

4. To prevent future issues, make sure you inspect your air conditioner regularly and replace any worn out or damaged parts.

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Frequently Asked Questions (FAQs)

How often should I clean or replace my air conditioner filters?

Your air conditioner’s filters should be cleaned or replaced at least every 3 months, depending on the manufacturer’s recommendations. If you live in an area with high levels of dust and debris, it is recommended to clean your filter more frequently.

What can cause my air conditioner to make strange noises?

Strange noises can be caused by malfunctioning motors, loose parts, frozen evaporator coils, and refrigerant leaks. If your AC unit is making strange noises, it is best to turn it off immediately and contact a certified technician for an inspection.

Is it normal for my air conditioner to emit a humming sound?

A humming sound from your air conditioner is typically normal, as this indicates that the motor is running properly. However, if the hum becomes loud or irritating, it is best to call a technician for an inspection.

How can I maintain my air conditioner to prevent similar issues in the future?

To maintain your air conditioner, make sure you clean or replace its filters regularly, inspect all components for signs of wear and tear, and check that the temperature settings are correct. Additionally, if you notice any strange noises coming from the unit, contact a certified technician immediately for an inspection.

Additional Resources and Assistance

DIY Air Conditioner Troubleshooting Videos

There are many tutorials available online that provide step-by-step instructions on how to diagnose and fix common issues with air conditioners. These videos can be a great resource when faced with a problem that you may not feel comfortable attempting yourself.

Online Community Discussion Forums

If you are looking for advice from other savvy air conditioner owners, consider joining an online community discussion forum. Here, users can ask questions and receive answers from experienced professionals and hobbyists alike.

Professional HVAC Technician Contact Information

If you need help with a more serious issue or prefer to have the problem professionally taken care of, look up HVAC technicians in your area. Most technicians will have their contact information listed online, so you can easily get in touch with them for a quote and to schedule a consultation.

Manufacturer’s User Manual and Support Hotline

For specific instructions on troubleshooting or repairs, check the user manual that came with your air conditioner. Additionally, many manufacturers have a customer service hotline that can provide helpful advice and assistance.


In conclusion, troubleshooting and maintenance of air conditioners may seem intimidating at first, but with the right information and tools, it can be a simple process.

Following the steps outlined in this guide will help you identify any issues quickly and safely so they can be repaired or replaced as soon as possible.

If you ever find yourself in a situation where you need assistance, don’t hesitate to reach out to a certified technician for help. Remember, taking the time to properly maintain your air conditioner today will save you from future headaches and costly repairs down the line.