9 AC Noises You Shouldn’t Ignore and Their Causes

Air conditioner noises can disrupt the peace and quiet of your home, especially if you’re looking for a relaxing escape from the Amarillo summer heat. If your AC is making noise, it can be equally as damaging as it is frustrating, and taking proactive steps is important to keeping your system running as it should.

Common AC Noises and Their Causes

Air conditioners make noises, such as some clicking or rattling when they turn on or a quiet hum during a cycle. The following noises, however, indicate underlying problems that may require professional repair.

1. Buzzing noises

Buzzing noises indicate several issues. Some air conditioners freeze over when under heavy strain or without regular maintenance, which results in inadequate air to the unit’s compressor and a resulting buzzing sound. Other components in the outside unit may also malfunction or break. For example, parts of the condenser fan and its motor may loosen or accumulate excessive debris that prevents proper function.

Electrical components also loosen or degrade over time. The contactor switch delivers high voltage to the coils and emits a buzzing sound when it wears out. Likewise, buzzing may signal loose wires, faulty circuit boards, and other electrical problems.

2. Hissing noises

Refrigerant, an essential substance for the heat exchange and cooling process, circulates through the AC system in the refrigerant line. Hissing from your AC can indicate a leak in the line, sometimes with a bubbling or gurgling sound. Refrigerant line damage requires professional attention.

AC hissing noises also point to other problems. Hissing may be a symptom of high pressure in the compressor — in some cases of a failing compressor, you’ll also hear grinding or humming noises.

3. Rattling noises

AC rattling noises usually signal loose parts or debris in the system. Resolving rattling noises can be as simple as removing sticks, dirt, or other debris from the outdoor AC unit. Screws loosen from AC panels and other parts, fan blades become misaligned causing a rattling as they bang against obstructions, and worn-out blower motor parts increase friction or shaking.

4. Clicking noises

It’s normal to hear a click from some air conditioner systems when they turn on or off. However, persistent AC clicking noises suggest problems with your thermostat’s electrical wiring, the relay process, or the contactor. A repetitive clicking sound may also indicate electrical issues elsewhere within the system.

5. High-pitched noises from outside the unit

Whether hissing or screeching, high-pitched noises from your outside unit point to problems with the compressor. Pressure buildup in your compressor usually causes about 15 seconds of high-pitched sound as the AC begins its cooling cycle. High-pitched squealing or screeching also points to mechanical issues such as a worn belt or motor bearing.

6. Grinding noises

Grinding noises almost always indicate mechanical wear or damage resulting from insufficient maintenance. Since grinding sounds typically come from two or more components rubbing together, leaving them unresolved often causes further damage to other mechanical components of your AC system.

Grinding from the outdoor unit could indicate worn pistons, which compress refrigerant gas, or point to a worn belt or seized fan bearing. These problems require a professional to diagnose and repair. Grinding from the indoor AC system suggests worn bearings or belts, although some parts only need basic maintenance and lubrication to eliminate the noise.

7. Screeching noises

Screeching noises are common with fan motor problems or compressor malfunctions, which can significantly strain your AC and potentially result in a system shutdown. Persistent screeching throughout the cooling cycle indicates a problem with the fan motor, and brief screeching at the start of the cycle suggests a compressor issue.

8. Banging noises

Whether a bolt, screw, connecting rod, piston pin, or other part, banging noises are a clear indicator that something in your AC system is loose or broken. Regardless of which component is responsible, banging sounds often result in serious damage to your system — a loose screw, for instance, can wedge itself in a crucial part of the fan motor and obstruct it during operation, or it can hit and damage the fan blades.

9. Whistling noises

Whistling noises usually trace back to vents and ductwork, when poor airflow creates high pressure. Imbalances in pressure strain your AC system and spike energy bills. Common airflow problems include:

• Dirty air filters
• Closed dampers
• Obstructed vents
• Ductwork blockages or damage
• Closed doors

In some cases, improperly sized, poorly installed, or faulty parts may cause whistling and airflow problems. These issues typically require an AC professional to assess and resolve.

Diagnosing and Fixing AC Noises

AC systems are complex and tricky to diagnose and fix, but a few DIY efforts might reduce or fix problematic AC noises and prevent further damage to your system. These include:

• Replace air filters: AC filters require replacement approximately every three months. Replacement prevents debris from building up, which limits airflow and causes your system to overwork.

• Inspect ductwork: Periodically check ductwork for cracks or other damage. Some damages only need a quick seal, while others may require professional repair.

• Open vents: Keep vents open and obstructed to help reduce undue strain and maintain optimal pressure in your system for minimal energy waste.

• Thaw unit: Turn off the unit and let it thaw if it freezes over. This sometimes fixes one-off noises and other problems. However, if your system freezes again, it’s likely you have a bigger problem and need an HVAC technician.

• Remove debris: Whether dust on the indoor unit or sticks, leaves, and other buildup on the outdoor unit, debris affects your system’s performance, causing it to overwork and potentially wear down parts faster than it should. Periodically clear away debris from the outdoor unit and dust or use a damp, soft cloth to remove dust and dirt buildup from the indoor unit.

Preventative maintenance to avoid AC noises

Preventative maintenance is the best way to keep your HVAC system performing efficiently and quietly. In addition to at-home cleaning and maintenance, routine professional HVAC inspections help increase your system’s performance, durability, and longevity. Services typically include:

• Full system inspection
• Air filter replacement
• Component lubrication
• Refrigerant level measure and pressure assessment
• Ductwork examination
• Blower motor cleaning and adjustment
• Condenser and evaporator coil cleaning
• Condensate drain line clearing and treatment

Schedule AC Service with Amarillo Air Conditioning

Keep your AC running quietly and reliably all summer long with maintenance and repair from our team at Amarillo Air Conditioning. Our fully licensed technicians provide expert, efficient, and courteous service, delivering 100% customer satisfaction. Contact us or book online today to schedule your service.

Frequently Asked Questions

Is it safe to run my AC if it’s making noise?

It’s safe to run your AC when it’s making normal operation sounds. Some sounds, such as banging and screeching, may indicate underlying problems that pose safety hazards if ignored. A professional HVAC technician will assess your system and tell you whether it’s safe to continue running.

Which noises require an emergency AC repair?

Some AC noises may be caused by minor problems, but it’s difficult to judge the severity of the issue without proper assessment. Taking proactive measures, scheduling prompt repairs, and maintaining routine maintenance will help minimize emergencies.