Questions and answers about high pitched and similar HVAC noises.

This article series helps diagnose and fix screaming, singing, squealing, trumpeting, water gurgling, whining, whistling, wuwuwu sounds at an air conditioner or heat pump.

Q&A on HVAC Noise Diagnosis of screaming, singing, squealing, trumpet, water gurgling, whine, whistling, wuwuwu sounds

These questions and answers about high pitched screaming, whining, or gurgling whistling sounds at air conditioning or heat pump equipment were posted originally

at HVAC NOISE-5 SCREAM SING TRUMPET WHINE WUWU - be sure to see the descriptions, recordings, diagnosis and repair suggestions in that article.

On 2018-07-25 by Breidys

Can someone tell me what is this noise?

On 2017-07-06 by (mod) - duct noise traced to zone dampener

Thomas,

Assuming that we are talking about an HVAC Zone dampener, you may need to disassemble it to find the loose part. Or example the central baffle may be loose on an arm that holds it in position inside of the duct.

If there is a complaint about air noise passing the damper, which is possible since the damper will not be perfectly airtight, it may be possible to adjust it's stopping position just enough to change the opening size to eliminate the noise.

On 2017-07-02 by Thomas

I went to a customer's house and found one of the dampner was slightly opening a little bit and then closing making a noticeable sound in the master vent because of the air getting by slightly.

Does this mean the Dampner is bad or can I tighten it some how? This is in residential home with three zones

On 2017-03-22 by (mod) - signs of a hard start compressor

Danny

It sounds like a hard-start compressor - could be a bad start/run capacitor or a failing motor or a control problem that's letting the compressor (sometimes) try to start against high head pressure.

On 2017-03-22 by Danny

AC compressor makes a grinding noise on cold start up ..... the next cycle on and off no grinding noise .... grinding Only occurs after the until has sat unused for 24 hours .... compressor starts and bzzzz perfectly for couple seconds then grinding noise for couple seconds then bzzz sound perfectly again throughout cycle ..... next start up no noise just perfect bzzzz sound

On 2017-01-13 by (mod) -

RE-posting (Comments Box blocks links for security reasons)

Tyler said:
Hi,
I am battling an intermittent noisy compressor on my geothermal unit. Sometimes it hums along perfectly and then will randomly go unstable and make bad sounds. It also starts off bad too.

Here are a couple videos. Any thoughts? Bad TEV "TXV" valve causing liquid to enter the suction side of the compressor?

Here is the unit starting, really bad noises coming from it.
...

Here is the unit humming along nicely and then around 1:15 into the video it has a random hiccup of bad noise. This sometimes lasts 10 minutes before it quiets down again.

On 2016-12-10 by (mod) - wowwow sound is from a compressor that is hard-starting

Barry

Sometimes the wowwow sound is from a compressor that is hard-starting. In that case you are hearing the electric motor trying to start against head pressure (or against a binding internal part), perhaps cycling on and off.

See https://inspectapedia.com/noise_diagnosis/HVAC_Noise_Descriptions_3.php#Huff

On 2016-12-10 05:36:01.730046 by Barry

The time period is around 1-2 seconds for the beat frequency. I had a ceiling fan that did the same thing. Maybe it's the motor?

On 2016-12-10 01:12:15.759790 by (mod) -

Barry, I'm not sure but some possibilities are in the article above at

WaWa, Wow wow sounds from A/C or heat pump system, diagnosis

On 2016-12-09 20:15:46.229481 by Barry

What would make what I call a beat frequency sound (nearest thing I can describe it with is the European police sirens that go up and down in frequency, like dee doo dee doo).

On 2016-11-23 03:54:01.626614 by Katy

Brand new noise. It is a quick scream at start like a small child who saw an insect. Lasts about 3 seconds at start. Is this related to humidity or 40-50 degree temperatures (ie, bearings or belt)?

Unit runs often because thermostat is inaccurate (yes, that is going to be replaced - a builder spec Honeywell that came with the house in 2006).

a/c is original unit. I rarely run heat above 20 degrees outdoors (townhouse is too well insulated, will hit 70 degrees inside when it is 32 outside with no heat operational, which I hate. I'm a 62 degrees woman all year round)

On 2016-08-30 15:26:42.175947 by (mod) -

FC

Some units have a high pressure safety valve. IT sounds as if the fan was not working and the compressor was overheating.

On 2016-08-30 13:10:28.498448 by fc3

Never mind.
The condensing unit fan was stopping and then starting again. When stopped, the head pressures went too high and the compressor screeched. Then, for whatever reason, the fan would start turning again, and as the condenser cooled and the pressure reduced, the noise lessened. A new fan motor solved the problem.

On 2016-08-30 04:48:34.876407 by fc3

I just experienced that loud squeal from my central A/C system.

Two or three years ago, the compressor of our old, 25 or so year old, system failed during a heat wave. I couldn't get anyone to do anything with it for "at least a couple of weeks," so I looked at alternatives.

All the service people told me that a new outdoor unit would have required a new indoor unit, but the ductwork is already undersized, so I'd really need a whole new installation - a couple of months to schedule and install, which was not happy news as the temperatures were in the 90s during the day and 80s at night with high humidity.

Long story short, I found a replacement compressor on-line and after talking to the vendor, selected one that replaced the one I had. I flushed the system with an approved cleaner, purged with nitrogen, and brazed the lines with the recommended material using new refrigeration copper fittings

. I pulled a vacuum on the system for 6 hours and then tested that it would hold 30". No leaks. The system has been working fine since then and the charge is correct as per the manufacturer's reheat chart (no TXV).

I just started to notice a periodic loud squeal from the outdoor unit that last less than a minute or so. I know the head pressures are high because the discharge air temperature from the condensing unit is unusually warm. Once the squeal stops, the condensors air discharge temp from the fan is noticeable cooler -- about normal for this unit.

Now what? Vacuum the system? Purge it? Install a filter? I have no idea what my next step is, but it's been working well, so I'd like to keep it that way.
I'm probably going to have to call someone in as this is a bit outside of my experience.

Thank you!!

On 2016-07-15 16:13:03.739657 by (mod) -

Sandra

Chirps usually indicate a control step cycle, sometimes a low battery in a remote controller.

On 2016-07-14 18:01:59.439569 by Sandra

Our Sanyo Wall-mount Air Handler (KHS1271) is makes an intermittent chirping noise. It can go several hours without the noise. It literally sounds like a little bird, possibly coming from the right hand side when looking at the air handler.

Any ideas?

On 2016-05-03 15:35:31.104736 by Michael

The house cools and everything works, but upon startup the condenser fan needs to be pushed to get it to spin...almost as if it is stuck until it needs that extra push...any suggestions? is this bearings... fan is hot to the touch until you give it the push to turn on

On 2015-06-14 14:03:05.403690 by (mod) -

did you see
WHINING A/C compressor/condenser or blower fan motor noise

in the article above?

On 2015-06-14 10:43:50.947350 by Jesse Joseph

in-sleave air conditioner makes whining high pitched noise
jesse772@gcom.com

On 2015-04-13 13:38:23.526950 by (mod) -

Thanks for the smile Mark. I sometimes hear humming sounds around the A/C for still other non-mechanical reasons: a happy AC repair technician, or angry bees.

On 2015-04-09 15:36:58.829390 by mark

Humming sounds are because the A/C doesn't know the words...

...

Continue reading at HVAC NOISE-5 SCREAM SING TRUMPET WHINE WUWU - topic home, diagnosis & repair, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

HVAC Noise Diagnosis Articles

• NOISES, HVAC SYSTEM DIAGNOSIS - home
• NOISES, HVAC SOUND DESCRIPTIONS
• HVAC NOISE-1 BANG BUZZ VIBRATE - banging, bearings, buzzing, thumping
• HVAC NOISE-2 CHATTER CLANK FAN GROAN - chatter, clank, clunk, cyclical sounds, fan noise, groan, growl, gurgle
• HVAC NOISE-3 HISS HOWL HUFF HUM - hiss, howl, huff, hum, groan, woo wuu wuff or humming noises
• HVAC NOISE-4 POP, RATTLE, ROAR, RUMBLE - loud start, popping, rattling, roaring, rumbling, running water
• HVAC NOISE-5 SCREAM SING TRUMPET WHINE WUWU - scream, sing, squeal, trumpet, water gurgling, whine, whistle, wuwuwu
  • SCREAMING or whistling or shrieking A/C compressor/condenser unit sounds - warning about high pitched sound from the compressor/condenser unit !
  • SILENCE no sound whatever coming from HVAC equipment?
  • SINGING, rumbling, whining A/C compressor/condenser or blower fan motor noise
  • SQUEALING air conditioner and heat pump equipment, diagnosis
  • TRUMPETING noises from compressor motors on A/C and heat pump systems
  • WaWa, Wow wow sounds from A/C or heat pump system, diagnosis
  • WATER SOUNDS in HVAC refrigerant piping or coils
  • WHINING A/C compressor/condenser or blower fan motor noise
  • WHOOSHING SOUNDS from the expansion valve
  • WHISTLING sounds at HVAC air handler or ductwork
  • WU WU WU sounds from A/C or heat pump system, diagnosis

Suggested citation for this web page

HVAC NOISE-5 SCREAM SING TRUMPET WHINE WUWU FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to BUILDING NOISE DIAGNOSIS

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