Diagnosing The Reasons Behind Noisy Ac Unit

Sometimes your A/c makes bizarre sound when it is powered on. In such conditions it is always recommended to contact an HVAC technician to know the reason behind the noise and resolve the problem ASAP. The noise could be due to a petty reason. But keeping it unchecked can cause a bigger problem. Here are the various types of noises that are usually heard from an air conditioner and the reasons that cause them-

High pitched sound

You hear this from the condenser unit as soon as your unit is on. The sound would usually linger up to 15 seconds. In this case it may also shut off and turn on frequently. The cause is most likely to be high pressure in the system. This is causing the compressor to scream. If you hear such sound shut the A/c off immediately. Running such a unit could be dangerous. Contact HVAC Repair Company near your house to come and take a look at the unit.

Clanking, hitting and knocking

This kind of sound is heard when the blower assembly becomes loose. The fan comes loose from the mount and wobbles and hit against the cage that houses it. There could also be an obstruction in the way of blade resulting in the sound. Turn off your unit. Keeping it on can cause further damages to the unit. Rattling sound is also heard when any of the component of the system comes loose.

Fizzing and gurgling noise

If this is the type of sound you hear from the system, there could be two underlying causes of this- the refrigerant is leaking and the sound is coming from condensate drain. If the leaking refrigerant from the copper tubing is creating this sound, call a technician ASAP. If the sound comes from the condensate drain, make sure that the drain has a trap.


This kind of sound comes from the outdoor unit. It is a very irritating sound that feels like a piece of metal hitting and rubbing against another. It is usually heard when the Fan motor is shot. You have to replace the fan motor immediately.


This sound is heard from the indoor unit. It will not be heard consistently; it will come and go but will be there regularly. This happens due to misaligned fan belt. The belt could also be worn out. The frequent expansion and contraction of the belt makes the sound come and go.


A humming sound is emanated by the air conditioner when the start capacitor fails. Buzzing sound is heard due to malfunctioning compressor, loose parts, damaged isolation feet, or frozen A/c.

Clicking sound

This is generally heard when there is a small obstruction in the outdoor unit’s fan. Sometimes this sound is heard along with unit not coming on. This could be due to electrical problems such as a faulty thermostat, a compressor problem or a defective scapacitor.



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