Diagnose humming air conditioner or heat pump noises or sounds at air conditioners or heat pumps or at heating systems & in HVAC duct systems or air handlers.

Air conditioner or heat pump noise diagnosis & cure: this air conditioning repair article series discusses the diagnosis and repair of air conditioning compressor noises which range in importance from normal (if annoying squeaks and squeals, to rattling loose bolts and hardware, to costly compressor damage indicating air conditioning compressor or A/C compressors at or near end of their life.

Humming Noise from A/C System: compressors or other electric motors in trouble

HVAC Air Handler OR Compressor/Condenser Humming Noise 10-point Checklist

1. Normal electric motor humming: nearly every electric motor makes a soft, continuous humming sound when running; this doesn't indicate a failure.
   
   When you swap in a new electric motor to an air handler or for a condenser fan, differences in manufacturer's motor quality may give you a motor that hums a bit louder.
2. Humming at transformer: where a low-voltage transformer is nearby, such as a 24VAC transformer operating thermostats or other device, check the transformer itself.
   
   See also LOW VOLTAGE TRANSFORMER, TRANSVERTER DIAGNOSIS
   
3. Humming Hard-starting motor: check for a bad start capacitor; ultimately check for a failing electric motor, bad bearing, bad winding, or failing compressor motor. Check current draw during start-up
4. Humming contactor: some failing contactors or relays hum rather than buzz
5. Humming vibration noises: check for loose motor mounts, out of balance fan in the air handler or at the compressor, worn fan bearings; also check for transmitted vibration noises carried by metal part like the refrigeration tubing
6. Humming air handler noises: after checking the blower fan motor and fan assembly for lost fan weights or a bent, damaged squirrel-cage fan and for bad fan bearings, check for icing or freezing starting a the cooling coil
7. Humming oil burner noises: are explained
   
   at OIL BURNER HUMMING NOISE
8. See ELECTRIC MOTOR HUMMING
   
   And because people's interpretation and naming of mechanical system noises varies,
9. Also see HVAC NOISE-2 CHATTER CLANK FAN GROAN - chattering, clanks, clunks, cyclical, fan, groans, growls, honking
10. Also see BUZZING NOISE DIAGNOSIS - extensive list; check first for most-dangerous: arcing buzzing contactors, relays, or any other arcing electrical component;

Additional diagnostic suggestions and detailed HVAC humming noise diagnostics are given in the Q&A found below.

The following HVAC noise descriptions are in this same noise category.

Related noises

• HVAC NOISE-3 HISS HOWL HUFF HUM - hiss, howl, huff, hum, groan, woo wuwuwu wuff or humming noises
  • HISSING SOUNDS, HVAC from A/C or heat pump system - separate article
  • HOWLING HVAC sounds from air conditioners, air handlers, blower fans, heat pumps, furnaces, duct systems & their motors
  • HUFFING sounds from A/C or heat pump system, diagnosis
  • HUMMING NOISES from HVAC SYSTEMS sounds from A/C or Heat Pump system condenser or air handler

Photo: a lost balancing weight on a squirrel-cage blower fan can cause vibration that may be described as "humming".

Fan counterweights are detailed

at BLOWER FAN ASSEMBLY CLEANING

...

---

---

ADVERTISEMENT

---

---

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2022-07-15 by InspectApedia-911 (mod)

@Anonymous,

Please see

CAPACITOR TYPES

On 2022-07-15 by Stephen

@InspectApedia-911,
So is there a run capacitor and a start capacitor ? Like two separate capacitors. Or is it just one capacitor that is the start and run capacitor in one? Also I can turn the blower wheel by hand. Would that mean the blower wheel is still good and something else is wrong?

On 2022-07-14 by InspectApedia-911 (mod)

@Stephen,

If you replaced only the start capacitor, maybe it's a run capacitor that's needed.

Keep in mind that often the underlying problem is a failing motor, perhaps a bad bearing - so the capacitor might give only a temporary improvement.

The fact that the blower wheel itself will spin by hand tells you that it's not bound up solid but it doesn't tell you if it's bearings are loose and wobbly or if there's a problem in the motor that only shows up as the motor tries to get up to speed.

On 2022-07-14 by Stephen

My blower motor wouldn't start. So I replaced the start capacitor and now it starts perfect, but It only runs for a minute or two then wines down and stops spinning all the way and just hums. I tried spinning the blower wheel by hand and it spins.

Anyone know what the problem could be? Its a Lennox furnace/AC blower motor. Thank for the help.

On 2022-07-08 by InspectApedia-911 (mod)

@Eric Wang,

Thanks for the update, do keep us posted. Sometimes a dirty or sticking TEV can cause vibrating noises

On 2022-07-08 by Eric Wang

@InspectApedia-911, They thought it might be too much refrigerant pressure, so they flushed it and toned it down. Worked for half a day but then the buzzing came back. Gonna try again today and I'll mention the thermostatic expansion valve you pointed out.

On 2022-07-06 by Anonymous

@Eric,

Good. Please let me know what the check finds, as it may help other readers.

On 2022-07-06 by Eric

@InspectApedia-911, Got a tech coming in 2 days.

On 2022-07-06 by InspectApedia-911 (mod)

@Eric,

Customer service technician to check the thermostatic expansion valve and let me know what you find.

On 2022-07-05 by Eric

I have a new AC unit, with outside unit and inside units. Blows cold, but after 2 months, there's a loud humming/buzzing noise coming from one of the inside units. The sound emanates from the inside unit all the way to the outside unit, along the inside of the ceiling. Maybe it is the entire pathway from the outside unit to the inside unit. The sound stops immediately if the cold air turns off, but fan stays on or if the entire unit is off. Please advise. Thanks!

On 2022-03-13 by Inspectapedia Com Moderator

@Tess,

In this article series you will see that we suggest keeping a sound event log that records surrounding conditions including time of day and what equipment is in use, as that can often help track down the source of an unexplained or undiagnosed noise.

On 2022-03-13 by Tess

In my bedroom, especially right under where I sleep and a spot near the bathroom and even in a spot in my kitchen all I here is a buzzing noise. I live in a condo on the 6th floor. I have been dealing with calls to and from my condo association and with the company that installed the hvac which is in the laundry room.

The buzzing is non stop and then it takes a break for a few days (peace!) and then it starts again and lasts for about a couple of days or so. The weird thing is it used to be non-stop but ever since I have been complaining now it just runs for a couple of days or so buzzing and then gives me some peace for a week or so.

The company said they can come out but every time I want them to come out the buzzing is nowhere to be found and they will get paid for coming out and for 1 hour's work which is costly. Obviously, I am not the only one who has these issues. I'm also aware that these complaints are barely taken care of.

I have not been able to sleep all Winter long. I just moved in during the Summer too. This is ridiculous. Hvac companies just want their money and could care less what your issues are. Obviously these are extremely common issues but yet they tell you they have never heard of such issues. Hmmm.

My problem is a buzzing noise (it used to be so much louder). It has driven me crazy and I have had no sleep on top of the fact no one wants to help. If they come out chances are the buzzing has stopped. What on earth is going on? All Summer long I had no issues.

On 2021-06-10 by inspectapedia.com.moderator - possible sources of Goodman AHU replacement motor humming

@Fredy, Thanks, that's an interesting question about AHU humming noise after a blower motor replacement.

At HUMMING NOISES from HVAC SYSTEMS HUMMING sounds from A/C or Heat Pump systems

I've collected what we know about humming noises in HVAC equipment - and I bet you already know all of them.

Why might the position of a blower squirrel cage fan (or "wheel") on the motor drive shaft make any difference in sounds from the air handler?

1. if the shaft and blower wheel are not properly aligned - which I've come across occasionally with pulley installations secured by a set-screw; this is unusual as most-often the clearance between motor shaft O.D. and squirrel-cage bearing and shaft I.D. is very slight; perhaps a third party motor shaft or blower wheel is being made to a different tolerance.

If this is the case when you tighten the set screw (e.g. an allen screw in a pulley or on a blower wheel) the wheel or pulley may be slightly mis-aligned.

In turn this may cause vibration, wobble, noise, and maybe early motor or bearing failure.

In extreme cases you can actually see the wheel is misaligned. I sometimes brace a screwdriver on a suitable point and hold it so its edge just clears the edge of a pulley or blower wheel. Then with POWER OFF (for safety) I spin the pulley or wheel, while moving the screwdriver blade closer to the pulley or wheel edge.

If there is a misalignment you'll hear or feel it just as the screwdriver blade begins to touch the wheel: if the feel or sound is not absolutely continuous then either there is a misalignment or you're not holding the tool securely.

2. Check that we have not lost one of the balancing clips off of the squirrel-cage fan blower wheel.

3. And check the items listed in the article above -like a bad start capacitor. (I was assuming, for examples 1 and 2 that the humming noise is NOT coming from the motor itself)

Keep me posted

On 2021-06-10 by Fredy - Some Goodman Air Handler Motors make humming noise

ive replaced many goodman air handler motors, but my coworkers have done the same job and somewho once they turn the unit on you hear a low humming sound coming from rhe airhandller.

Could it be the position of the blower wheel on the motor which causes the low hum?

On 2021-03-30 by (mod) - rooftop AC unit humming noise complaint

@Alison,

Above on this page we list some common causes of humming noises in buildings.
But
as you phrase the problem description you're hearing the noise when the A/C is OFF. If you're sure that's right, then we need to look elsewhere for the source of the noise:

- what other equipment in the building is in operation
- could other outdoor noises such as street noise or noises from a nearby building or transformer be picked up by your building's HVAC system or ductwork
and
- even if you cannot identify the noise source (*which is most important), if you can identify the path of noise transmission (for example through metal ductwork) it may be possible to modify components to reduce noise transmission

It's perfectly fair for the HVA company to say they can't diagnose a noise that is not present when they are on-site. You or someone with more expertise is needed to do that observation and diagnosis when the noise is occurring.

Also take a look at our HOW TO USE a SOUND EVENT LOG and in the printable log sheets that article provides

- also found in the ARTICLE INDEX as sometimes keeping track of the other items suggested on that document can pinpoint a noise source.

On 2021-03-30 by Alison

I live on the top floor of a condo. Above the roof are 3 a/c units. I have an intermittent humming noise (60 db) and vibration though the ceiling in my bathroom which sounds in my bedroom. It starts throughout the day and during the night when it appears no a/c is on and actually started in Jan. Other condo owners can hear the noise in the hall but of course it is much less than in my condo.

The h/c company said that they need to hear the noise but can never come out when it is noisy. It is affecting my sleep because of the vibrations. The HOA is sympathetic but keep telling me it must be my condo because it isn’t bothering anyone else. Any ideas on who can help me discover what this is and how to solve

On 2021-02-06 - by (mod) - humming noise heard at air duct

Deborah

If your heat is from a heat pump it sounds as if your backup heat system (that kicks in when outdoor temperatures are too cold for the heat pump to work) is not turning on.

Some diagnostic suggestions are at BACKUP HEAT for HEAT PUMPS https://inspectapedia.com/aircond/Heat_Pump_Backup_Heat.php

but the first thing to check is that the circuit breaker(s) for your heating system and backup heat (in the electrical panel) are not tripped off.

If I'm mistaken and your heat is by a conventional oil or gas furnace see

NO HEAT - BOILER https://inspectapedia.com/heat/Heating-Boiler-Diagnosis.php if your heat is by forced hot water baseboard or radiators or steam

NO HEAT - FURNACE https://inspectapedia.com/heat/Furnace-Diagnosis-Repair.php if your heat is by forced warm air

Since your earlier message mentions "duct" I think

NO HEAT - FURNACE may be the place to start.

On 2021-02-06 by Deborah Chance

I’m cold! The system shut down at 11:30pm last nite

Humming coming from heating system near duct house not getting heat
System is also shutting off but comes back on with that humming noise

Question: humming from vent fan

(Aug 30, 2015) Bill B said:

I have a large vent fan (Dayton 4HZ396)for a photo darkroom in my home. It is controlled by a rheostat switch. All of the equipment is about 6 years old and is seldom used. I recently tried to turn fan on and the motor (1/4 horsepower) would only hum, but not start.

There are no obstructions and the breaker is not tripped. Any ideas for a novice who knows enough to not get electrocuted? Might it be the rheostat or would that be too easy? Thanks

Reply:

Bill,

One of the first things I look for when there is a "humming" noise from mechanical systems is a motor that is having trouble starting.

I suspect that in the case you describe

- the fan motor is seized
or
- something is obstructing the fan blades
or
- the fan uses a start/run capacitor that needs replacement
or - less likely
- the voltage is inadequate

See if the fan spins freely when flicked with screwdriver

See if the fan will start and run if when it's humming you try the same trick

Watch out: you can get your fingers cut off or you can be shocked or killed if you do not know how to do this test safely.

If it runs then it probably needs a start capacitor

This humming motor problem shows up at air conditioner compressors , fan motors, oil burner motors, furnace blower fan motors, water pump motors as well as at the motor of the fan on an air conditioning compressor/condenser unit.

See BURNED-OUT COMPRESSOR and

also HARD STARTING COMPRESSOR MOTORS

Also see ELECTRIC MOTOR WON'T START / RUN

Your fan motor may be the problem. The root cause could be a failed or frozen electric motor but sometimes a less costly problem has occurred: a failed start / run capacitor on an electric motor. Not all motors have a start capacitor but many do so it's something to look for.

See CAPACITORS for HARD STARTING MOTORS

Details about all types of hard-starting or "non-starting" electric motors are

at ELECTRIC MOTOR DIAGNOSTIC GUIDE - home

Question about humming sounds from the air conditioner:

I have a 13 year old Armstrong AC, 4 ton, 10 S.E.E.R. in our house. For the past 5 years (ever since we got into the house), the outdoor compressor unit has been making loud humming sound. The sound does not sound like humming if I stand next to the compressor unit outside.

However, inside the house, the sound is of humming. The AC has worked fine - no leaks, cools properly etc. I have had it serviced but every time the service person chalks the noise to age and recommended a new AC w/o any investigation. It could be just age but I'd welcome suggestions things I can check for myself.

I followed the two lines (thin copper line and the larger/covered in black line) running between outdoor and indoor AC units. If I put my ear next to the larger line, I can clearly hear the humming sound along its length as I move from the outdoor AC unit to the indoor condenser unit. I can also feel vibrations/tremors on this larger line.

Would appreciate any suggestions. Thanks - VikI

I have been hearing a humming when my air conditioner is running now for about a week but the air is cool and working O.K. but this is coming from the compressor outside and wondered what it could be??? - Joyce Ballard

There is a humming noise coming from the Heat Pump AC unit when the thermostat is in the cool setting, but the thermostat is set below room temperature (air conditioner not running). If I move the switch on the thermostat to the off position the humming stops in the unit. Do you have any idea what is wrong? Thanks, Don 6/3/12

Hi, I live on the second floor of a condo and hear a loud constant low pitched humming noise coming from inside the wall where the tubing enters the unit from the outside and travels up the wall and across the ceiling to the internal blower.

The sound is not present when the heat is on. It is a deep harmonic mmmm sound and has a vibration component. The AC blows cold and otherwise seems to be working. The compressor is 10 years old. - Barbara Rich 4/9/12

Reply: Pinning down the exact humming noise source on HVAC equipment: refrigerant line noise transmission, loose component parts, low voltage transformers, and hard starting -electric motors

A humming noise that you are hearing at the larger refrigerant line (the suction or "low pressure" line) can help you trace the noise to its source: the indoor air handler or the outdoor compressor-condenser. Knowing the source can help track down a detail that may or may not be repairable, such as a loose part, loose compressor mount, or worn out compressor internal parts.

Often pipes transmit vibration into a building chiefly because they are attached to building walls, ceilings or floors that in turn act as a giant speaker cone. If the piping is rubber mounted or cushioned with foam you can often eliminate the noise indoors. (Of course you may still need an equipment repair.)

Watch out: a humming noise coming from an electric motor or A/C - Heat Pump compressor motor that is not actually starting and running is likely to indicate that the motor is unable to start, and is at risk of overheating or damage. Humming from a motor that can't start is sometimes repaired by replacing a bad start/run capacitor, but if the motor is actually failing and seizing, it will need replacement.

Sources of humming sounds from HVAC systems are outlined at HUMMING sounds from A/C or Heat Pump system

which usually leads diagnosticians

to COMPRESSOR CONDENSER NOISE

and in that article at our description

of ELECTRIC MOTOR HUMMING

In the most expensive case we're looking at

a BURNED-OUT COMPRESSOR

In a different category, humming on oil fired heating equipment may be a normal sound transmitted to the building via oil piping attachment points. A/C refrigerant piping may also transmit equipment noises if it is not properly routed and mounted.

Electric motors (other than HVAC compressor motors) also make humming noises when running or when trying unsuccessfully to start -

see ELECTRIC MOTOR NOISE DIAGNOSIS

our ELECTRIC MOTOR DIAGNOSTIC GUIDE.

Often the problem is a bad start capacitor.

See details at CAPACITORS for HARD STARTING MOTORS

Refrigerant line vibration can transmit buzzing humming noises throughout a building.

See details at REFRIGERANT PIPING INSTALLATION

Aside: humming on oil fired heating equipment may be a normal sound transmitted to the building via oil piping attachment points. A/C refrigerant piping may also transmit equipment noises if it is not properly routed and mounted.

Question: high frequency or two-frequency hum since new, installers say normal, stops if I press on the enclosure

2015/11/08 Vince said:

I have a new home in Florida and have the HVAC on a regular 6-month inspection. I noticed a 2 frequency hum from the start, advised the installers, and they said it was normal. At each 6 month inspection, I bring it up again - the outside compressor drones on and on with the 2 hums, steady.

I have asked each tech about it (4 times now!) and each say it is normal. It wakes me up at night and drones on and on when it is running

I have noticed that if I press on the outside shell of the unit, the droning stops to a steady, normal fan sound. The techs re-tighten the housing, but the hums start up within the first or second cycle on. It is driving me crazy! Any ideas?

Reply: tips for stopping vibration hum traced to the metal enclosure or motor mounts of an AC system or heat pump

Vince

Kudos to you: it goes to show that a motivated smart homeowner may find out something valid that the techs, being rushed by the service manager to make as many calls as possible, simply brush off as "they all do that". Bah!

I would look with care for the vibrating parts: if as it seems the vibration sound is being made by transfer of normal vibration - say from the compressor motor or fan motor - to the A/C housing shell, you should be able to tighten the shell or cover screws to fix the trouble;

if necessary one could even add a couple of screws provided you take care that no sharp screw points come anywhere close to a wire or refrigerant tube or anything else that could be damaged.

Check also for loose motor mounts and for missing plastic or foam vibration dampener fittings where wires or tubing pass into or out of the building wall or the compressor/condenser cover.

Also check any wiring strain reliefs and look for anything else that can move, vibrate, and be tightened or secured.

When you've found a suspected culprit and have tightened a fastener, a dab of silicone sealant can help keep a screw from backing out.

Less often but once or twice I fixed such a problem by inserting a small scrap of rubber roofing material (EPDM) between two metal surfaces that were vibrating, then re-tightening the appropriate screws.

Question: Condenser not working, humming sounds

My a/c condenser is not working, the fan blades do not turn, when I lower the indoor thermostat and then go out doors to the condenser pad, I hear " a humming click" approximately every twenty seconds or so, as if the unit is trying to turn on.
What is wrong ? - Hilary

Reply: humming indicating hard-starting or frozen compressor motor

Hilary it sounds as if you are describing a hard-starting or stuck compressor motor. The click you hear may be the the result of the system turning itself off (unable to start) followed by a cool-down interval, and then the system tries again.

You need a diagnostic service call and if in luck it could be a a bad start capacitor. Out of luck, a shot compressor. Other problems can also cause the compressor to have trouble starting, such as a bad refrigerant control valve.

Reply: Rattling, followed by Low Humming Noises and hard starting compressors

Kim: that humming sound makes me think your compressor is either suffering hard starting or is at end of life and close to seizing.

Question: intermittent humming, pounding, wum wum sound

(Feb 24, 2014) Jim Dinsdale said:

We are hearing a intermittent humming, that turns into a pounding "wum, wum" noise through the wall that connects our stone cottage with our neighbour. She has an air source heat pump that runs her hot water and central heating.

The noise can go on for hours with what sounds like a motor starting up, revving up at about 180 beats per minute, then reaching speed, then after a minute or two fading away for a few minutes before starting again. It can happen anytime day or night but is most distressing at night, typically occurring from the early hours until about 9am or later.

I would be grateful if you could suggest what this might be. Our neighbour says she can hear the noise but denies it is coming from anything in her house. We had no problem until she had the system installed three years ago, and on several occasions when we have complained, the noise has stopped for a few days.

Reply:

Jim,

The first step in an issue like this noise problem is to obtain an impartial and reliable witness to document the problem and its apparent source. What you describe might be a piece of equipment with a failing control or motor - like a heat pump fan or compressor motor.

It's no surprise that people's hearing ability varies widely as does their ability to tell direction of sound.

Question: ventilator fan noise, humming

(Apr 18, 2014) Charles said:

I am suffering from fan ventilator noise, i.e., loud humming, that's operative 13 hours a day 7 days a week. I need to find a way to block the noise. I can't hear myself think, and apparently the Department of Public Health feels the decibel level is "legal." What to do?

Reply:

Charles,
Assuming you've checked with your doctor or audiologist and are sure there is no medical issue involved and that the noise is for certain traced to the fan you mention, it would make sense to start by determining if the equipment is functioning normally and properly.

Fan motor noise, including humming, could be an indicator of a hard-starting electric motor that in turn indicates a risk of burn-up that in turn could be a fire risk. So have a qualified technician check out the equipment.

If it is determined that the noises that bother you are normal equipment behavior, then you'll want to review our article series on sound control in buildings, beginning at

SOUND CONTROL in BUILDINGS

Question: humming AC, fan speed varying

(June 26, 2015) Bill said:
My ac unit is cold . It has a humming sound now. Fan will run and the slow down and then speed back up . Repeat.. Also the unit I've very warm to touch. Fan motor maybe? Thanks

Reply:

I'd check for low voltage and for a seized motor.

Question: faint humming from the HVAC heater

(Oct 17, 2015) Kathy said:
My Heater always has a lf ain't humming sound as it starts for a few seconds before heat pumps out from vents. I just took up all carpeting and a louder sound in one vent in the master bedroom has started before the usual humming sound before the heat blowing out?

I have a Coleman unit which is only 11 yrs old. It seems odd that only one vent exhibits this noise. I checked other vents in other rooms and waited for kick on of heat and nothing other than usual sound?

Is this a concern?

Reply:

Yes: it sounds as if a motor is having a hard time starting: your service tech (whom you should call) may find a bad start relay or capacitor.

On 2021-02-28 - by (mod) -

@LUIS D LOSADA, I would expect the A/C Service Company to be able to find and correct the problem

On 2021-02-28 by LUIS D LOSADA

I live in a condo and have a chronic buzzing/humming from an unknown neighbor's AC. It is heard mostly at night and weekends (person works?). During day very mitigated (no Ac just fan?). Management is not around at peak noise times. Cant seem to find where it comes from. Is there a company I can hire?

On 2020-12-03 by (mod) - My dog gets super stressed when the heat pump is on: dog sensitivity to noises

Sure, or a low frequency sound - dogs' hearing is far more sensitive than ours.

• Storengen, Linn Mari, and Frode Lingaas. "Noise sensitivity in 17 dog breeds: Prevalence, breed risk and correlation with fear in other situations." Applied Animal Behaviour Science 171 (2015): 152-160.
• Levine, Emily D. "Sound sensitivities." In BSAVA manual of canine and feline behavioural medicine, pp. 159-168. BSAVA Library, 2009.
  

On 2020-12-03 by Karen

My dog gets super stressed when the heat pump is on. Could it be a high frequency sound only he can hear?

On 2020-09-22 - by (mod) -

SG

I'll be glad to help, but to be clear, InspectApedia.com is NOT a company that sells anything, no product, no service, nothing.

You might call the district manage again, starting with a thank you for their prior response which, I'm sure, was at a cost of many thousands of dollars.

Then you might note that because the vibration continues and is in your experience extreme, the manager might want an independent expert to diagnose the problem. Otherwise there is a real risk that an installation or support or mounting problem could damage and thus risk the expensive investment that Walgreens recently made by replacing the equipment.

InspectAPedia.com provides building and environmental diagnostic and repair information. In order to absolutely assure our readers that we write and report without bias we do not sell any products nor services, nor do we have any business or financial relationships that could create such conflicts of interest.

On 2020-09-22 by SG

Hi,
My name is Sherry, I live in Brooklyn. My home is pretty much attached to a Walgreens and there is something wrong with their HVAC units on their roof. In my entire home you can feel these units vibrating and humming.

This feelings goes through your body and causing a lot of problems. People can not stay in the home, thats how bad it is

. I have spoken to the district manager and after a couple of months they had the units replaced but it still does the same exact thing.. I don't know what it is or why its doing this. Maybe they were not installed properly. I am hoping your company can help.

I can be reached via email or phone at 347-407-2216. I am a teacher and work from 8-2:30 so if you can call after 2:30 that would be much appreciated.

On 2020-09-09 - by (mod) -

Check out the humming noise sources described at https://inspectapedia.com/noise_diagnosis/HVAC-Humming-Noise-Diagnosis.php

On 2020-09-08 by Jim

I have a fairly loud humming sound when the ac is running coming from the furnace. the furnace sounds normal when the heat is on

On 2020-07-10 - by (mod) -

super
let me know what you find

On 2020-07-10 by George t

Thanks! I’ll dig around tomorrow and see if I can’t find it.

On 2020-07-10 - by (mod) - return air filter humming noise

George

I'd look first for an air leak or a loose duct mount, on the theory that the restriction caused by the filter causing air to move in through a small unintended opening or leak

On 2020-07-10 by George T.

When my AC unit comes on the return filter in the ceiling “hums”. I have 2 returns, only one does it. If I remove the filter it stops. I put in a new filter and after about 2 hours it started doing it again. Any ideas?
Thank you!

On 2020-05-29 - by (mod) - humming vibration noise source

Jerry

It sounds to me as if you've identified the problem: noise and vibration transmission from the A/C unit to the building floor structure; ask your service tech to check first for loose parts, loose mounting, or other operating defects that need repair; if the problem remains I'd ask for sound-isolating pad or mounts.

On 2020-05-29 by Jerry

We have a humming sound that we can't locate and a vibrating we can feel in the floor.

The humming/vibration stops when we turn off the breaker to the central air unit. However, the central air unit still functions and cools fine when it is on. Any idea/suggestions on what could be going on would be greatly appreciated.

On 2020-05-22 - by (mod) - mechanical transmission of vibration from motor to refrigerant line to building framing or wall materials.

Chris

Thank you for the follow-up - that will certainly help other readers.

In sum, I take it that there was mechanical transmission of vibration from motor to refrigerant line to building framing or wall materials.

On 2020-05-18 by Chris - HVAC duct air velocity noise cured

Problem solved. Installers climbed in attic .. all duct looked good

They decided to run new duct line return to get more airflow. Before they did. I said wait you run lineset outside house but hum is still there ir u put up hand on drywall you can feel vibration.

So a thinking man would assume hum coincides with vibration. So they moved until away from house 6" and pulled lineset away from house. BINGO WAS HIS NAMEO. hum vibration gone.

So moving lineset helped 40% but keeping off house decorative track /enclosure was the other 60%. Problem solved . Thank you for your advice .. I hope this helps someone else.
ChrisF.

On 2020-05-15 - by (mod) - low hum vibration noise in Amana HVAC unit

Chris

Let's try to get to the actual physical component that's humming or vibrating in your Amana furnace

Changing the filter in and out - having an effect on the noise - suggests to me that air velocity may be causing vibration on a duct or air handler component. That would be an indoor sound.

But you think it's the compressor/condenser outside. Puzzling.

Yes vibrating refrigerant lines, picking up vibration at the compressor/condenser can carry that movement into walls, floors, ceilings, etc. where it appears indoors.

But I'd start by a careful trace of all the ductwork, starting right at the air handler.

On 2020-05-15 by Chris

I have 2 yr old Amana 16 seer ac and Amana dual speed furnace. With added April aire 20x25x4 filter. Since install I've had low hum vibration in house . For 2 yrs. They said it was normal , "I don't think so. " .

I finally called amana. Now they wanna fix it. They ran new ref. Lines outside the house as the old ones where in wall. Got a little better don't feel vibration in wall anymore. I've told them for 2yrs. Now when I remove the filter the hum vibration stops when I reinstall the filter hum immediately returns .

There is no hum at the furnace Airhandler or outside just in house . I think its coming from the compressor but the fan running makes it hard to pinpoint. They are coming back Monday to check return lines in attic . They think unit is not getting enough return air? Any ideas?

On 2020-01-04 by (mod) - humming from failing gas furnace

Could be a failing motor or bad bearing or a failing low voltage Transformer

On 2019-12-29 by Susan Chelune

Why is the pump to my gas furnace making a humming sound?

On 2019-12-12 by (mod) -

That sounds like a failing motor or control, Jim. Humming motors usually mean a failed motor or a bad start/run capacitor.

On 2019-12-04 by Jim johnson

Therm set at 70, temp inside is 73. Blower outside is humming loadly for a min and stops. Why?

On 2019-06-23 by (mod) - humming

I would be careful about reaching into any equipment is you could get shocked or be injured in some other way such as by moving Parts. However if you could take a picture of what you think is humming that might be helpful. Perhaps it's a bad relay or a bad low voltage Transformer.

On 2019-06-23 by Karen

My A/C isn't turned on but there is a humming coming from inside.

When A/C goes on, this often stops but this afternoon the humming started and despite the A/C going off and on, it is still humming. I can reach in and feel exactly where the noise is coming from but I can't find a diagram.

The units is a furnace A/C inside closet in house. The fan, etc is outside. The A/C works fine and blows cold but next to the unit is a black weird looking box with everything plugged into it.

This is in the closet. It is the thing that is humming. I just turned the fuse off outside to the A/C unit and that noise is still going on. I have no idea what is going on. This is 3 year old A/C that is serviced regularly. What should I do? What is going on?

...

Continue reading at HVAC NOISE-3 HISS HOWL HUFF HUM - loud start up noises, popping, rattling, rumbling, running water or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see HVAC HISS HOWL HUFF HUM NOISE FAQs - questions & answers posted originally at this article

Or see these

Recommended Articles

• BLOWER FAN ASSEMBLY CLEANING
• ELECTRIC MOTOR HUMMING
• HUMMING NOISES in BUILDINGS - complete list of sources of humming sounds at or in buildings
• 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
• 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 sounds, whine, whoosh, whistle, wuwuwu, or silence
• LOW VOLTAGE TRANSFORMER, TRANSVERTER DIAGNOSIS
• NOISES, HVAC SYSTEM DIAGNOSIS - home
• OIL BURNER HUMMING NOISE

Suggested citation for this web page

HUMMING NOISES from HVAC SYSTEMS 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

Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia

Ask a Question or Search InspectApedia

Try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Note: appearance of your Comment below may be delayed: if your comment contains an image, photograph, web link, or text that looks to the software as if it might be a web link, your posting will appear after it has been approved by a moderator. Apologies for the delay.

Only one image can be added per comment but you can post as many comments, and therefore images, as you like.
You will not receive a notification when a response to your question has been posted.
Please bookmark this page to make it easy for you to check back for our response.
Our Comment Box is provided by Countable Web Productions countable.ca

Citations & References

In addition to any citations in the article above, a full list is available on request.

---

ADVERTISEMENT

---