You know the sound of your A/C. It’s a steady, comforting hum that means “cool air is coming.”
But suddenly, that hum changes. Maybe it’s a high-pitched shriek when it starts up. Maybe it’s a loud buzzing sound. Or worse, a metal-on-metal banging that shakes the floor.
Your A/C is trying to talk to you. Unlike your car, which has a “Check Engine” light, your A/C uses sound to tell you something is wrong. Ignoring these sounds can turn a $200 repair into a $5,000 replacement.
As Fast Air Conditioning Repair, we speak the language of HVAC. This expert guide translates the most common scary noises and tells you exactly what to do.
The High-Pitched “Screech” or “Squeal”
What it sounds like: A loud, piercing scream that usually happens right when the unit turns on, then might fade away. The Likely Culprit: This is usually a Fan Belt (on older units) or a Fan Motor Bearing going bad.
- The Risk: If the bearing seizes up completely, the motor will burn out.
- The Fix: Turn it off. This is often a simple part replacement if caught early.
The Constant “Buzzing” or “Humming”
What it sounds like: An angry beehive inside your outdoor unit. The unit might not be running, but the noise is there. The Likely Culprit: This is almost always Electrical. It could be a failing Capacitor (the battery that starts the unit) or a stuck Contactor (the switch).
- The Risk: Electrical components can overheat or cause a short circuit.
- The Fix: Call a pro. High-voltage electrical repairs are dangerous for DIY. We can usually swap out a capacitor in minutes.
The “Hissing” or “Screaming” Whistle
What it sounds like: A balloon letting air out, or a high-pressure whistle. The Likely Culprit: A Refrigerant Leak or high internal pressure.
- The Risk: If your system is leaking refrigerant (Freon/Puron), it is not only bad for the environment, but it will also freeze up your coils and kill your compressor.
- The Fix: Turn the system off immediately. Running a system low on refrigerant is the fastest way to destroy the compressor.
The Metal “Clanking” or “Banging”
What it sounds like: Someone threw a wrench into a dryer. A rhythmic, heavy metal sound. The Likely Culprit: This is serious. It could be a loose fan blade hitting the cage, or a part inside the compressor has broken loose.
- The Risk: If a fan blade flies off, it can slash through the condenser coil and destroy the unit instantly.
- The Fix: Do not run the system. This requires an immediate professional diagnosis.
Silence is Golden.
A noisy A/C is a broken A/C. The longer you let it scream, bang, or buzz, the more damage it does to itself.
At Fast Air Conditioning Repair, we diagnose with our ears and fix with our expertise. We carry the most common motors, capacitors, and fan blades on our trucks so we can silence that noise on the very first visit.
Contact us 24/7 if your A/C starts making a noise you’ve never heard before. We’ll get your home quiet and cool again, fast.