noisy air conditioner

Your Loud, Annoying, Noisy Air Conditioner

  • July 28, 2015
  • By MR COOL

It’s summer. It’s hot. Air conditioning is great. Unless…you can’t even get a good night’s sleep thanks to your noisy air conditioner.

You can’t go without A/C, so what do you do? Is that noise even normal? Should you call someone?

Don’t worry. MrCool is here to help.

Diagnosing a Noisy Air Conditioner

There is one big question you should ask about a noisy air conditioner: “Is the noise normal or the sign of a problem?”

Depending on your air conditioner’s age, the noise might be normal. Older units lack the insulation and noise-reducing technology many new units have as standard features. What you want to do is listen for a few key indicators:

  • Grinding: Grinding is bad. If you hear it, it’s probably coming from the fan motor. The bearings in the motor can wear out after a long operating life. When they do, they start grinding. You’ll need to get the fan motor replaced, since total fan failure is probably not too far off.
  • Rattling: A rattling noise can be a big deal or a little one. Sometimes leaves and twigs can get caught in the vents, and sound really bad when you hear them. They’re not a big deal. Clean them out and you’re good. Rattling inside the compressor itself is a problem. It means operating wear and tear is starting to build up, and your compressor may be on its last legs.
  • Hissing: If you hear a sharp hissing noise coming from the unit itself, that means one thing: refrigerant leak. Modern refrigerants are rarely dangerous to humans, but replacing it is expensive. Contact an HVAC professional immediately when you hear that noise.

Those are the major problem sounds you need to listen for when it comes to worrying about a noisy air conditioner.

And, remember, if the unit’s just loud, it’s probably just old. The only way to permanently solve that is with a new air conditioner that, purely by coincidence, we would be happy to sell you.

34 thoughts on “Your Loud, Annoying, Noisy Air Conditioner”

  1. How loud is the outdoor unit? We will have on the exterior bedroom wall. Will this be noisy if it’s mounted there? And is vibration associated with it being mounted on the wall?

    1. The outside condenser is not very loud especially compared to a traditional air conditioner condenser. It has rubber pads you can use during installation to mitigate any potential vibration.

  2. My inside unit is humming, a low grade constant low humming, that sounds like white noise, but t is so annoying.

  3. My unit is making a high pitch whining noise on start up after a minute or two it goes away, any suggestions?

  4. 18k single zone unit about 2 years in service. Makes a click, click sound about three consecutive times when the unit is turned on and the louver is moving to its open position. Also make the same sound periodically while on. No noise when louvere is closing. Any ideas?

    1. You may want to check if your louvers are aligned appropriately. Softer noises may be common during operation, but if it sounds loud, obtrusive, or as if things are grinding together, please give us a call at 270-336-0457 as quickly as possible.

  5. I have 3 units in 3 different bedrooms within my house. From an AC perspective i assume they run from the one unit that sits outside. All of the units (3 inside and 1 outside) are less than a year old. So far this year i have turned the AC on 2 times. the first time we thought someone was breaking into the house in the middle of the night. It sounded like some kind of wild animal was growling in the living room. The second time i turned on the AC the same thing happened in bedroom 1. I turned off unit and it stopped. an hour later it happened in the living room. same, i turned off and it stopped. 2 hours after it happened in bedroom 2. The sound is a loud grinding and sounds like its breaking. Any advice?

  6. i have three air handlers an 18k and two 9k the 9k units during operation sound like water boiling is that normal

  7. My newly installed MC 5 ton inverter runs very quiet in heat mode until what seems to be the compressor kicking on. Then I hear a noticeable vibration noise (enough to wonder what the neihbors think). 45 deg outside today so not related to ice. i then put wood blocks under the unit / slab to absorb the vibration and that helps quite a bit. is this compressor noise common? is it possible i lost a little r410a causing the noise? I have a 50ft line set.

    1. You may want to have an HVAC professional make sure that the unit is set correctly. Otherwise, please give us a call at 270-366-0457. It should not have lost any refrigerant, unless the vibration was extreme.

  8. My mr cool I door fan surges. It is about 2 years old but has only been installed for about 2 months. It has done this since it was first installed 2 months ago.

    1. We apologize for this. Please give us a call at 270-366-0457 as soon as you possibly can so that someone from our tech support team can assist you with this.

  9. Loud vibrations and grinding from the unit from the time of purchase. Had it for about a year now and it comes and goes. Also receive a P0 and P4 error code as well. I believe I still have warranty on this unit please help.

  10. I have a 18k Mr cool single unit. The AC is now making a high-pitch noise whenever the fan is running, doesn’t matter the mode. The higher the fan speed the louder the noise. Happens even when only the fan is running. Not sure what the issue is but it’s annoying. The unit heats and cools without issue. Is it possible to only change the indoor unit? The outdoor unit works fine

    1. Please give us a call at 270-366-0457 as soon as you possibly can so that someone from our tech support team can assist you with this issue.

  11. Hello, I just installed my ac split unit and when I turn the ac unit to cool, there’s a very quiet hissing sound that kicks on for just a small amount of time and then goes away. It’s very intermittent and sounds pretty normal but I just want to make sure.

  12. Our 36k DIY unit has been working well for several years now. Recently it has started making a couple noises.
    1. Sometimes a barely audible high pitched noise like a fan bearing.
    2. Normally the blower exit air noise is very quiet but randomly exit air noise surges for a second or so and then quiets down again, then repeating every 15 seconds or so.

    Unit is cooling and heating normally just a minor change in the noise level.

    1. These are likely benign noises caused by normal use of the system, but you may want to give us a call at 270-366-0457 if the noises give you further concerns.

  13. I have to say I have been very disappointed in our unit. From day one it has sounded like a freight train every time it kicks on. It is so loud my husband and I have started wearing ear plugs at night or just shutting the unit off. We have spent over $3000 for cost and installation plus service calls. All of this during the Pandemic which didn’t help either

    1. Depending on how your system is operating, you may want to give us a call at 270-366-0457. If the noise does not align with what is listed on page 39 of the manual, you may want to get in contact with us.

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