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Why Is My Aircond Making Noise? Strange Sounds and What They Mean

A healthy aircond should be quiet enough that you barely notice it’s running. When your AC starts making unusual noises, it is trying to tell you something is wrong.

We know how frustrating it is to have your sleep interrupted by a rattling unit, especially during a humid night in Kepong or Kuala Lumpur. These sounds are often more than just a nuisance; they are early warning signs that you may need aircond repair.

Our team at AC Service Pro has decades of experience decoding these mechanical signals. Here is your guide to understanding what your air conditioner is saying and when you need to act.

Normal AC Sounds

First, let’s establish what is normal for units operating in Malaysia’s tropical climate.

• Gentle humming: This is just your compressor doing its job.
• Soft whoosh: You should hear air flowing consistently through the vents.
• Quiet click: The unit makes this sound when turning on or off.
• Thermal “Pop”: Plastic casings often expand and contract in our heat, causing a random popping sound.

These are signs of a healthy AC. You can generally ignore them unless they get louder.

The Noise Guide

🔊 Rattling or Vibrating

Urgency: Low to Medium ⚠️

What it sounds like: Loose, shaking, or vibrating sounds coming from the wall unit.

Possible causes:

• Loose screws or front panels.
• Debris like twigs or dried leaves in the outdoor unit.
• Loose fan blade.
• Unit not mounted securely to the wall plate.

What to do:

1. Check for visible loose parts on the casing.
2. Tighten any accessible screws with a screwdriver.
3. Clear debris from around the outdoor compressor.
4. If the noise persists, call a technician to check the mounting.

Risk if ignored: A minor rattle can vibrate components loose over time, leading to cracked piping or leaks.

🔊 Buzzing

Urgency: Medium to High ⚠️⚠️

What it sounds like: An electrical buzzing or humming that is significantly louder than the usual operation sound.

Possible causes:

• Loose electrical connections.
• Failing compressor.
• Refrigerant leak.
• Faulty contactor (a common electrical switch).
• Frozen evaporator coils preventing airflow.

What to do:

• Turn off the AC immediately.
• Check if the filter is clean, as a dirty filter can cause freezing.
• Call a technician for a professional diagnosis.

Risk if ignored: Electrical issues can be a fire hazard, and a strained compressor is one of the most expensive parts to replace.

🔊 Clicking

Urgency: Low to High ⚠️ (depending on frequency)

What it sounds like: Sharp clicking sounds when the AC runs or tries to start.

If clicking only at start/stop: This is likely normal relay operation.

If clicking continuously:

• The “Cicak” Factor: We frequently find that lizards (cicak) have crawled into the control board and shorted it out.
• Defective control board.
• Failing thermostat.
• Capacitor problem.

What to do: Continuous clicking usually means an electrical failure. Call a technician to inspect the PCB board.

🔊 Squealing or Screeching

Urgency: High ⚠️⚠️⚠️

What it sounds like: High-pitched screaming or squealing that is painful to hear.

Possible causes:

• Bearing failure in the fan motor (most common in split units).
• Fan blade rubbing against the casing.
• High internal pressure, which is dangerous.
• Worn fan belt (only applies to older central units).

What to do:

1. Turn off the AC immediately.
2. Do not restart it to “test” it.
3. Call a technician right away.

Risk if ignored: You risk complete motor seizure, which turns a RM250 repair into a much larger replacement job.

🔊 Grinding

Urgency: High ⚠️⚠️⚠️

What it sounds like: Metal-on-metal grinding, similar to a mixer without ingredients.

Possible causes:

• Motor bearings are completely worn out.
• Fan motor is failing.
• Compressor internal pistons are damaged.

What to do:

• Turn off the AC immediately.
• Call a technician.

Risk if ignored: This sound means metal parts are destroying each other. Ignoring it will lead to total system failure.

🔊 Hissing

Urgency: High ⚠️⚠️⚠️

What it sounds like: A continuous sound of air or gas escaping, like a deflating tire.

Possible causes:

• Refrigerant leak (R32 or R410A gas).
• Internal valve leak.
• Compressor issue.

What to do:

• Don’t ignore this sound.
• Call a technician for leak detection.

Risk if ignored: Loss of refrigerant stops cooling and damages the compressor. It is also harmful to the environment.

🔊 Banging or Clanking

Urgency: High ⚠️⚠️⚠️

What it sounds like: Loud banging from the indoor or outdoor unit, as if something has broken off.

Possible causes:

• Loose or broken part thrashing inside the unit.
• Compressor mounting springs have broken.
• Fan blade hitting an obstruction.
• Compressor internal damage.

What to do:

• Turn off immediately.
• Do not run the AC.
• Call a technician.

Risk if ignored: A loose part can smash into other components, destroying the entire unit in seconds.

🔊 Bubbling or Gurgling

Urgency: Medium ⚠️⚠️

What it sounds like: Water bubbling or a “shisha” pipe sound coming from the wall unit.

Possible causes:

• Bio-Jelly Blockage: Our humidity often causes algae and jelly-like slime to block the drain pipe.
• Refrigerant leak.
• Air trapped in refrigerant lines.

Occasional gurgle: This can be normal refrigerant flow.

Continuous bubbling: This usually points to a drainage issue or a gas leak.

What to do: If the sound persists, have it checked to prevent water leaking onto your wall.

Quick Reference Chart: Noise & Estimated Cost

We have compiled this table to help you estimate the urgency and potential cost of repairs in the KL area (2025/2026 estimates).

Sound	Urgency	Possible Issue	Est. Repair Cost (MYR)
Rattling	Low	Loose parts/debris	RM80 - RM120 (General Service)
Buzzing	Medium	Electrical/Capacitor	RM150 - RM250
Constant Clicking	Medium	PCB Board/Lizard	RM300 - RM600
Squealing	HIGH	Fan Motor Bearings	RM250 - RM450
Grinding	HIGH	Motor Failure	RM350 - RM600
Hissing	HIGH	Gas Leak	RM180+ (Depends on Gas type)
Bubbling	Medium	Blocked Drain/Gas	RM150 - RM180 (Chemical Wash)

The Hidden Cost: Noise & Your TNB Bill

You might think a noisy AC is just annoying, but it is also expensive.

We have observed that a unit struggling with worn bearings or a dirty compressor pulls significantly more power.

This inefficiency can increase your monthly electricity bill by up to 25%.

It effectively means you are paying a “noise tax” every month you delay the repair.

When to Turn Off Your AC Immediately

🛑 Stop the AC right away if you hear:

• Squealing or screeching.
• Grinding metal sounds.
• Loud banging.
• Any sound getting progressively louder.

Running an AC with these sounds can turn a minor repair, like a RM150 bearing fix, into a RM2,000 full replacement.

Prevention Tips

Most AC noises come from poor maintenance. You can prevent them with:

1. Regular filter cleaning: Do this every 2-4 weeks to keep airflow smooth.
2. Standard servicing: Schedule this every 3-4 months to tighten parts and check gas.
3. Chemical wash: Perform this every 6-12 months to remove the “jelly” buildup in pipes.
4. Prompt attention to new sounds: Don’t ignore changes in pitch or volume.

Hear Something Strange?

Don’t let a small noise become a big problem.

We are ready to help you diagnose the issue quickly and honestly.

Contact AC Service Pro for:

• Expert diagnosis by local specialists.
• Transparent repair quotes in Ringgit Malaysia.
• Same-day service available in Kepong and KL.
• Warranty on all repairs.

WhatsApp us and describe the sound. We will let you know if it is urgent or can wait.