If your AC is making noise, it might be time to contact an HVAC technician for an assessment. An air conditioner that’s noisy could indicate a range of problems – some more serious than others.
Water Sounds
Dripping
As a normal byproduct of the cooling process, your air conditioner will produce some condensate. These droplets drip into the drain pan, which is connected to a line to the outside. Hearing an occasional drip is normal, however, if the dripping becomes incessant it’s time to check your drain pan to ensure water isn’t accumulating there. A full drain pan could point to a variety of issues including clogs in your drain line, frozen evaporator coils, and improper AC installation. These issues require a professional HVAC assessment so that proper steps can be taken in order to avoid any further damage to your unit.
Running Water
If you hear something that sounds like running water, it’s likely that the drain pan is already full and overflowing. Whether the pan is filling up because your line is clogged, your AC coils are frozen, or due to improper installation, it’s important to contact RedHome as soon as possible.
Bubbling or Gurgling
Bubbling or gurgling sounds coming from the AC can indicate a pressure issue caused by a refrigerant leak. Refrigerant leaks require a proper diagnosis and professional repairs.
Rattling Sounds
Yard Debris
It’s not uncommon for small yard debris to end up around and even inside your outside HVAC unit. However, if you hear dirt, gravel, sticks, or other yard fragments being knocked around inside your AC, it’s crucial to call a professional to remove them as they can do serious damage to the inner components.
Fan Alignment
If the outside fan isn’t properly aligned, whether due to poor installation or damage from yard debris, you’ll likely hear a rattling sound as the fan knocks against the unit’s wall.
Broken Motor
When the AC motor isn’t working properly, parts inside your unit that rely on the motor to work correctly can become loose or misaligned and begin to rattle.
Loose Hardware
Over time, screws inside the AC unit may become unfastened, causing components like the condenser or evaporator to vibrate and rattle.
High-Pitched Sounds
High-Pitched Sounds Inside the Home
REDUCED AIR FLOW
Chances are, this is happening because of reduced airflow. If airflow to your HVAC unit is impeded, you’ll hear a high-pitched whistling sound. When airflow is reduced, your AC is working harder to pull air through the return ductwork, which causes unnecessary strain on the entire system.
Dirty air filters are among the most common reasons for slowed airflow and whistling sounds in the home. Your filters should be replaced every 3 months, and more often during the peak season.
But keeping your air filters clean prevents more than just noise. Because dirty filters cause your system to work harder, they can quickly lead to a range of other issues including damage to the coils, overheating, worn parts, and more.
Closed or obstructed vents are another reason why you might be hearing a high-pitched whistling noise whenever your AC is running. Ensure you keep the areas around your vents clear of furniture, boxes, and heavy window treatments, and that your vents are open in every room – even in rooms you don’t use.
MOTOR BEARINGS
If you’re hearing high-pitched squealing or whistling sounds coming from the indoor unit, you might be dealing with worn or damaged bearings. The motor’s bearings will naturally wear out with age and can be replaced by a professional HVAC technician.
High-Pitched Sounds Outside the Home
REFRIGERANT LEAK
If you’re hearing a whistling noise after the AC kicks on, it could be due to increased pressure inside the compressor, a sign of a refrigerant leak. If you suspect a refrigerant leak, it’s important to contact an HVAC professional right away and discontinue the use of your AC to avoid additional damage.
Humming and Buzzing Sounds
Faulty Motor
If the AC is humming but the fan isn’t spinning, a malfunctioning motor could be the culprit. A broken condenser or blower motor that needs to be replaced but is still getting power will make a noticeable and loud humming or buzzing sound.
Bad Contractor Switch
If you hear a loud buzzing at the outdoor unit and the AC isn’t kicking on, it’s possible that the thermostat isn’t able to signal the unit to cycle because you have a bad contractor relay switch. A bad contractor results in a humming noise.
Refrigerant Leak
If you see ice on your unit, it might be accompanied by a buzzing noise. Together, these could be caused by a refrigerant leak, obstructed airflow, or a malfunctioning motor.
Electrical Issues
Loose wiring or bad electrical connections can cause a buzzing sound around your AC unit. Additionally, if your system becomes overloaded but your circuit breaker won’t trip because it’s faulty, you may hear a consistent electrical humming noise. These are both dangerous situations and require prompt attention from a licensed professional.
Squealing Sounds
Worn Motor Bearings
Air conditioners work in part by drawing air across the condenser coils with the help of a fan. This fan is powered by a motor, which contains bearings that become worn over time. Worn bearings will result in a squealing or grinding sound coming from your outside unit.
Compressor Pressure
The AC compressor helps release heat from inside your home via the condenser coils. When the compressor, located in the outdoor unit, makes a squealing sound, it could be a sign of high internal pressure. This is an issue that needs to be addressed as soon as possible.
Clicking Sounds
Outside Unit Is Clicking
If the unit starts making a clicking sound that starts slow and gets faster, it may be the sound of the outdoor fan coming into contact with debris inside the unit or an issue with fan alignment.
If the compressor is failing or the controls and relays for the compressor are damaged or malfunctioning, this can also cause a clicking noise that can be heard from the outside unit. Compressor failure may also be accompanied by vibrations.
A loud clicking noise from the outside unit could also mean that your capacitor is in trouble. The capacitor is responsible for providing the jolt of electricity required to start your HVAC’s motors and keep them running. A failing capacitor makes a clicking sound.
Clicking Inside the House
A clicking noise inside the house likely indicates an electrical problem, such as a problem with your thermostat is another control.
AC Clicks But Doesn’t Start
When you’re hearing clicks but your unit isn’t starting, the issue likely lies with your control board, the thermostat, or the capacitor.
Hissing Sounds
Refrigerant Leaks
If your unit is hissing, it may be the first symptom of a refrigerant leak. As the compressed gas escapes, it makes an audible hissing noise even when your unit isn’t running. In addition, you may hear gurling or bubbling. If this is accompanied by ice on the unit or leaking water, you’re almost certainly dealing with a coolant leak.
Compressor Pressure
The compressor moves pressurized refrigerant through the system. If there’s an issue with the compressor that’s causing the pressure to build up or escape, you may hear a high-pitched hissing noise from the exterior unit for 10-15 seconds right after the AC kicks on. If you hear a hissing or whistling sound coming from your AC compressor or your unit is starting and stopping more than usual, shut the unit off immediately and contact a professional.
Malfunctioning Reversing Vale
If you have a heat pump, that hissing sound could be a sign that the valve responsible for reversing the direction of air moving through your heat pump is broken. The sound you’ll hear will be audible from the outside unit and will be constant.