Photograph of  This new compressor was placed directly against
a brick wall. One third of its condenser coil cooling ability was blocked.Sound & Noise Recordings of Air Conditioners, Heat Pumps, Furnacs
Recordings of HVAC noises help diagnose mechanical system problems
     

  • NOISES, HVAC SOUND RECORDINGS - CONTENTS: recordings & comments about them aid in the diagnosis & how to epair air conditioning & heat pump compressor noises, air handler noises, duct work sounds, or noises traced to air filters, or to HVAC controls
  • POST a QUESTION or READ FAQs about HVAC system noises & sounds as troubleshooting aids for equipment repair
  • REFERENCES

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HVAC sound & noise recordings:

Example sound recordings of various noises or sounds made by air conditioners, heat pumps, furnaces, ductwork, or HVAC controls & filters. We discuss how we approach listening to and interpreting noises coming from an air conditioning or heat pump system & what different noises may mean.

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Sound Recordings of A/C & Heat Pump System Noises

Sound & video recordings of air conditioning & heat pump compressor noises are provided & discussed here.

Article Contents

CONTACT US by email to submit your own noise or noise+ video recording or if you cannot find the HVAC noise diagnosis information you need.

Normal Air Conditioner or Heat Pump Noise Recordings

Below are recordings and comments about abnormal HVAC system sounds.

Buzzing: Intermittent Buzz Sound Recorded at the Compressor/Condenser Unit

Start tracking down the cause (and cure) of noises from your air conditioning or heat pump system by listening carefully to determine the location of the sound.

This brief video contributed by one of our readers demonstrates start-up troubles and characteristic buzzing at the outdoor fan-compressor unit. The unit is unable to start.

Some guesses at what the noise heard in this cyclic compressor/condenser buzzing noise might mean are given below.

Details about buzzing noises in HVAC systems are at HVAC NOISE group 1 - banging, bearings, buzzing


Possible causes of this particular A/C (heat pump) compressor start-up failure noise - a repeated buzz sound include

  1. A seized compressor motor - likely
  2. A bad contactor relay - very possible
  3. A bad start-run capacitor - very possible
  4. Low voltage delivered from the electrical panel to the equipment - possible, less common, can be due to bad electrical connections or to arc-burned aluminum electrical wiring
  5. Low electrical service voltage - possible, less common

CONTACT US by email to submit comments or suggestions about these noise recordings or to submit your own HVAC noise recording for publication, diagnosis, commentary.

Cycling: Intermittent but Regular Cycling Buzz Sound Recorded at the Compressor/Condenser Unit



Note: this 5-second recording is a large 8MB .mp4 file. Once loaded you may want to re-play it a few times to listen carefully to the cycling sounds of this compressor unit. - Ed.

Start tracking down the cause (and cure) of noises from your air conditioning or heat pump system by listening carefully to determine the location of the sound.

This brief video contributed by one of our readers demonstrates a repetitive cycling or humming/buzzing sound at a Carrier brand outdoor fan-compressor unit.

The unit seems to be running but not properly, possibly this is a hard-starting compressor problem.

More suggestions about what the noise heard in this cyclic compressor/condenser buzzing noise might mean are given below.

Details about buzzing noises in HVAC systems are at HVAC NOISE group 1 - banging, bearings, buzzing

Reader comments

My HVAC unit started making these cyclical noises [in the recording given just abovce]. It seems as if something is out of balance. The compressor will ramp up and then start back at the normal volume, and then ramp up again. Is this something to worry about? - S.Y. 29 June 2015

Rattling Air Conditioner Compressor-Condenser Unit Noise

This brief video contributed by one of our readers demonstrates a horrible rattling sound at an air conditioning system compressor/condenser unit start-up.

MISSING SOUND - I'm working on it - Ed.

More about this class of rattling HVAC system noises is at HVAC NOISE Group 4 - loud start, popping, rattling, rumbling, running water

 

 

Screaming: shrill high pitched sounds at the Air Conditioner or Heat Pump

This noise and the reader's video were originally reported in the FAQs at HVAC NOISE roup 5

Possible causes of this noise: we, like Jeremy, think this may be a bad blower bearing

Also see Whistling Sound Recordings Below.

Whistle: Very High Pitched Whistling Sound at the Air Conditioner

This brief video contributed by one of our readers demonstrates a very high pitched sound at an air conditioning system compressor/condenser unit.

Discussion of this noise is just below.

This HVAC noise category is closely related to

HVAC NOISE group 5 - scream, sing, squeal, trumpet, water gurgling, whine, whistle, wuwuwu

 

 

  • The sound goes for about 7 or 8 minutes before the unit starts. I do not see anything moving when it occurs. When the blades start spinning, the sound stops.
  • It always occurs at the start of the unit running....all day and all night.
  • We have lived here almost 3 years and I would say I have noticed for at least the last year.
  • The unit came with the house so it is 10 years old.
  • The unit has no company logo on it but I searched the address and model number...I think it was made by Tempstar, a part of International Comfort Products. The model number is NAC242AKA5.

Possible diagnosis:

  • sound coming from an electronic start-up component
  • sound from a poorly-lubricated or seizing fan motor bearing

Check for and use (if found) lubrication ports on the fan motor & bearings (with power off!)

Check for loose or wobbly fan bearings (with power off!)

AC or Heat Pump Noisy Start-up Sounds

  • AIR CONDITIONER START NOISE recording. This recording of noisy start-up sounds can indicate failing compressor motors, relays, fan motors, controls

Window Air Conditioner Noises

 

 

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NOISES, HVAC SOUND RECORDINGS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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