Is your air conditioning making loud clackety-clank sounds? Do you have noisy air vents?

As the temperatures continue to climb, the chances of you needing air conditioning repair goes up.

HVAC tune-ups are highly recommended at the beginning of any major season change to ward off costly repair (and eventually replacement) costs. However, regular tune-ups do not guarantee no problems. As with anything, there comes a time when a repair or replacement is needed. One of the first indications of this is a strange sound coming from either your indoor or outdoor A/C unit.

NEVER ignore loud or strange noises coming from your HVAC system.

Here are 5 of the most common air conditioning noises, what they mean, and how to fix them:


Buzzing sounds could indicate a problem with your compressor motor.


If you hear a hissing sound, this is a dangerous sign that you have a major refrigerant leak that should be repaired as soon as possible. Sometimes the hissing sound will follow a trumpeting noise at shutoff.

You may also see or hear a slight bubbling sound, which can indicate a refrigerant leak as well.

Hissing and bubbling noises should be addressed as soon as possible. Turn your HVAC system off and call a qualified technician to fix the leak and recharge the refrigerant before turning your A/C back on.


If your air conditioner is starting up and makes a slight squealing noise, don’t worry. This is probably just the sound of the compressor getting going.

If the sound of the screeching and/or squealing is unusually loud or long, it may be the result of unwanted internal pressure. If the pressure reaches a certain point, the A/C system should automatically turn itself off, but if it doesn’t, you may hear a loud screeching/squealing sound. Turn the A/C off immediately and contact your local HVAC technician.


Loose screws, bolts, and other parts can cause clanking, clicking, rattling, and other metallic sounds. There may also be a problem with the fan or motor. Loose bearings, unlubricated parts, and other unfixed components are common culprits.

If you hear loose parts in your air conditioning unit, avoid a major repair by turning the unit off and contacting your local HVAC company as soon as possible.


If you hear a humming followed by a slow startup, you could have a starting capacitor that needs to be repaired or replaced. If you air conditioner hums and hums without ever starting up, turn the unit off and call a technician. Sometimes the starting capacitor seizes and needs professional help.

If you hear any strange sounds coming from your air conditioning system this summer, contact OnTime Service for HVAC service done right.

We are dedicated to providing professional, on-time HVAC, plumbing, and electrical service to Hoover, AL and the surrounding area.

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Call OnTime Service at 205-942-1405 to schedule your next HVAC, electrical, and plumbing service. We can help protect your home from flooding damages, install sump pumps, and much more!

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