Aircon Making Noise: Which Sounds Are Normal

The sounds below are sorted into normal and not normal. If yours is in the second list, our home service aircon repair covers rattling, grinding and buzzing units, and the technician finds the cause at your house.

Sounds that are normal

A click when it starts or stops

Normal as the unit switches on or off. A click that keeps going while it runs is not.

Water or gas flowing

Refrigerant moving through the pipes, and condensate running to the drain.

A short squeal as some units start

Normal at start-up on some models.

The hum of the fan and the compressor

The sound of it working, steady and even.

• 1From the indoor unit. Whistling usually means a dirty filter. Bubbling and hissing can mean a refrigerant leak or water in the system. Clanking is something loose, often the blower fan.
• 2From the outdoor unit. Humming that grows louder and buzzing point to an electrical fault. Rattling is loose parts or debris. Screeching points to the fan motor or the compressor, and grinding to the motor or another moving part.

Sounds that are not normal

1. 1 Four sounds are normal. A click as it starts or stops, water or gas moving through the pipes, a short squeal as some units start, and the steady hum of it working.
2. 2 Three start with a check. Clean the filter, make sure nothing is touching the unit, try the remote. If the sound stays, book a technician.
3. 3 Hissing or bubbling needs a check-up. It can be a refrigerant leak, and a leak does not seal itself.
4. 4 The last three mean switch it off now. Then book a repair.

Three checks before you call

1. Stand by each unit and find which one the sound is coming from.
2. Look for anything touching the outdoor unit or caught in it: a branch, a plastic bag, a loose bracket. Samsung’s advice for banging and rattling starts with a level unit and nothing in the way.
3. Clean the indoor filter. A clogged one is behind the whistling and buzzing on both makers’ lists.

If the noise is still there, note what it sounds like and when it happens, at start-up, all the time, or only when the compressor kicks in. That description saves the technician time at the house.

Questions people ask

Why is my aircon making a loud noise?

Loud banging, rattling or clanking is usually something loose, such as the blower fan or a panel, or debris in the outdoor unit. Screeching and grinding point to the fan motor or the compressor, and a hum that keeps getting louder points to an electrical fault. Each of those needs a technician.

Is it normal for an aircon to make a clicking sound?

A click when it switches on or off is normal. Clicking that keeps going while it runs is not, and can mean a loose fan blade or a fault in the controls.

Why does my aircon sound like running water?

Usually because it is: refrigerant moving through the pipes and condensate running to the drain both make that sound, and both are normal. Bubbling or gurgling that is new or getting louder can mean a leak or water where it should not be, and is worth a check-up.

Can a noisy aircon be dangerous?

A high-pitched whistle or scream can mean a refrigerant leak or very high pressure, and Samsung’s advice is to switch the aircon off immediately. A burning smell with any noise means switch it off at the breaker.

Book the repair

Tell us what the noise sounds like, which unit it comes from, and the town. See what aircon repair covers, or book a check-up if you are not sure what it is.

Other guides

• Aircon capacitor: what it does and the signs it has failed

  The humming outdoor unit, the fan that will not spin, and why the capacitor is tested first.

• Aircon freezing up: why ice forms and what to do

  Ice on the indoor coil or the pipes, how to thaw it safely, and the three causes behind it.

• Aircon not turning on: what to check, and the 3-minute wait after a brownout

  Remote, breaker, the compressor’s restart delay, and the flashing lamp that means a technician.

• AVR for aircon: when you need one and how to size it

  What an AVR does in a brownout, which units already protect themselves, and sizing it from the nameplate.

• Aircon watts: how many watts a 1 HP aircon uses, size by size

  Running watts and kWh per hour for each size, how to read the nameplate, and starting watts for a generator.

• Types of aircon: split type, window type, portable and centralized

  How each is installed, how noisy and costly to run it is, which rooms suit it, and what a clean has to reach.

• What is freon, and why your aircon should not need a yearly refill

  The sealed loop, why low gas means a leak, the three refrigerants in Philippine units, and the refill myth.

• Aircon HP and room size: what each size cools, 0.5 to 2.5 HP

  The square metres each size suits in a shaded room and a hot one, with the arithmetic behind 0.6 HP.

• Aircon cleaning schedule: what to clean, and how often

  The filter every two weeks, a full clean by how hard the unit works, the deeper clean, and when in the year to book it.

• Common aircon problems, symptom by symptom

  Not cold, weak air, water inside, a smell, ice, noise, tripping and blinking: what each points to and what you can check.

• Aircon lifespan: how long it lasts, and repair or replace

  How many years a unit usually gives, what shortens it, and the signs that a repair is no longer worth it.

• Inverter vs non-inverter aircon: which costs less to run

  Kilowatt hours side by side at 2, 4, 8 and 12 hours a day, and the kind of use where a non-inverter is still fine.

• What size aircon for a bedroom, living room or kitchen

  Room by room: what each kind of room adds to the size you need, worked through for a sample two-storey house.

• Aircon energy saving tips that lower the bill

  Where the heat gets in, the setting and the fan, the timer, the cleaning, and reading the DOE energy label.

Sources: Samsung Philippines, “What should I do when air conditioner is noisy?”; Hitachi, “AC Noises: Why Does My Air Conditioner Make Weird Sounds?”; Carrier, “What is an AC Capacitor?”.