Homeowners Don't Know What Their HVAC System Is Doing

“tonight we started hearing intermittently (like every 10 minutes) this long, very loud, almost vibrating noise coming from our utility room. I've attached a video and the utility almost captures the noise that lasts close to a minute. it seems to be coming from the metal column that I am videoing, but it's hard to tell. I am definitely not very knowledgeable about this stuff. Can someone help me figure out what this is and how we fix it? Thank you! submitted by /u/Insta-taine”

“This happens only from time to time and only during very hot days. It will run normally and all of a sudden goes into this weird rattle noise. It has been serviced this year, topped off with refrigerant after 4 years lost just a small amount of gas. Ideas as to the rattle? Appreciate any suggestions. submitted by /u/rafalski8 [link] [comments]”

“Hvac company put an electronic filter in my unit. Three days ago. It’s brand new. The box (return??? Intake?? Idk) it went in is old from like the 80s and fiberglass. I used to just put normal 20x20 paper filters in. This filter is always buzzing like this very loudly and then sometimes it does a long “beeeeeeeeeeeep” - which I can’t tell if it’s beeping or if maybe the filter has a gap between the wall and the air is just whistling through it? I tried to look up if maybe I need to change it or”

“This is what my A/C unit sounds like on start up. From inside my house. At the end of the video you can hear what it sounds like the whole time its running, the sound doesnt really improve. We had a tech come out and look at it. He bailed before we could talk to find out what the problem was and keep an eye on it. It sounded better, still loud but less like. Buzzing i guess. But two weeks later its back to this. Does anyone know if we will need major repairs? It cools the house fine. Its just so”

“my internal filter is making a HORRENDOUS noise whenever it’s turned on, you can literally hear it shaking through the walls even with the door shut. I’ve tried submerging it right to the top but that didn’t help either 🥲 it’s unbearably loud and I really don’t want to fork out for a new one if it can possibly be fixed so any advice that isn’t just “more water” would be appreciated. model is AQQA Aquarium Internal Filter AQ126-18W submitted by /u/Silver_Goose4401 [link] [comme”

“Can anyone tell me why its making this loud noise! It blows cold air sometimes it doesn’t and im in the master bedroom the whole bedroom doesn’t get cold besides one area submitted by /u/Jealous-Charity-8445 [link] [comments]”

“so I recently moved in about a month and a half ago to my first apartment and when I go to do my monthly filter cleaning I notice a noise from the room but I thought it was just the AC but I heard it louder today and got more curious and saw this. any advice pls submitted by /u/Imaginary_Lab6744 [link] [comments]”

“My husband just changed the air filter and now the system is making a humming/buzzing noise. It only seems to hum when this door is closed. We took the filter out to see if it would still hum without it, and that is what the video is showing here. The new filter is the exact same size, merv rating, and brand. Any ideas? submitted by /u/No-Act-7767 [link] [comments]”

“So ever so often when the air conditioner is shutting down it creates this banging sound that's coming out of the intakes throughout the house. It doesn't happen all the time it's occasionally and then it goes away for a long periods of time. AC is running fine cooling to correct temperatures. Zoning is working fine in the two sections. And it only happens every once in awhile and then it goes away? Any ideas? Thanks guys submitted by /u/Charleslorenz0 [link] [comme”

“12 year old system, started making this noise today. I have an appt for service monday, but want to see if there are any ideas on what is happening and ultimately if its going to cost a lot of $$$? Lastly, should i turn it off to protect it? Edit: the noise I'm worried about is the higher pitch whirring and the cuts in normal operation. I posted an additional video of the fan running normal. It sounds fine for about 10 minutes after turning off and back on again. Thanks! submitted by &”

“This is an 11 year old - 3ton Ameristar Heatpump. Its getting cool air into the house but not efficiently. Anything below 76 degrees and the unit will keep running (live in FL). submitted by /u/ChiefRunningWaters [link] [comments]”

“Not every day, but maybe 3 times a week my furnace makes a noise that sounds to me like something is falling down it. It sounds like a stick is falling down a metal pipe. I don't think it is sticks, it seems to be the exact same noise each time. I thought it was an animal at first but it only makes the sound once then stops. I think maybe its some metal piece that is shifting with the temperature changes but I don't know for sure. submitted by /u/BathTimePoet [link] [co”

“Hey, I have an old Lenox furnace and for the last couple days it will make a noise like it's reving up, this only lasts about 5-10 seconds and happens every couple hours but is not consistent. Unopened it up to take a look and noticed my pilot light is out, not sure if this is related, just off because the gas hasn't gone out and o didn't shut it off. I appreciate any help. submitted by /u/User837265 [link] [comments]”

“The other night a storm came through, and the power blinked off and on while the AC was running. It was only off a second or so, and the AC cut off then restarted. When it came back on it was much louder. It didn't really sound too different than normal other than being noisier than usual. It was pretty alarming so I quickly shut it off at the thermostat. I turned it back on after a little while and it was back to normal. Any idea what was going on? submitted by /u/Rochefort [lin”

“Have tried turning the thermostat completely off and still happens. Each morning around 5am I hear the sound in the video clip on and off repeatedly for most of the morning. Eventually stops trying. The blower doesn't seem to go, and it also seems to happen sometimes when the A/C is running. Any theories? submitted by /u/letitrideforward [link] [comments]”

“So I have this AC that does its job perfectly fine. What I've noticed though is that since a couple months ago, when the outside unit kicks on, it makes this loud... Idk how to describe it... Clunk or whatever that I can hear from 4 homes away. Also occasionally my lights flicker the tiniest bit when it starts cooling. Is this something that can be serviced or is it just aging? submitted by /u/Wallaroo_Trail [link] [comments]”

“Hi, a couple of days ago this vent started to get really loud, I didn’t think much of it. But now it sounds like an engine. Anyone know what might be the issue? Would it be something I can fix myself? submitted by /u/ace_spaded [link] [comments]”

“I know it’s dusty and I’m sure that’s a part of it but I’m almost afraid to touch it. I put a new filter in 2 days ago and maybe I knocked a wire or something?? The AC turns on but not nearly long enough to cool the apartment, 20mins max (1bed 1bath in Florida). I’m calling maintenance in the morning and I can just wait but is there anything to do aside from sweating it out? My cats are looking at me like they’re going to eat me, my dog is acting like I’ve utterly betrayed her… we’re just all ho”

“We left for the weekend and came back to a warm house and our hvac making this noise. What can it be? submitted by /u/RecognitionChoice [link] [comments]”

“Hi I just replaced hvac last week , and this is career brand. The noise seems really off, I contacted my installer but he doesn’t respond me so far and it makes me really concerned. Can I ignore this noise? As long as it won’t impact on its lifespan or functionality I won’t mind. Thank you submitted by /u/ddarky85 [link] [comments]”

“I can hear this sound throughout the whole house. It will occasionally stop but will come back and hasn't stopped in the past hour. I changed the filter but it did stop the noise. See attached video. submitted by /u/Polkawillneverdie17 [link] [comments]”

“Had my AC replaced with a heat pump a year and a half ago. When operating in cooling mode, the refrigerant line makes a gurgling whooshing boiling sound and it sounds like the pressure builds until a relief valve lets off some pressure. Seems very abnormal but curious what the potential issue is and what needs to be done if anything. submitted by /u/omidimo [link] [comments]”

“About a week ago I replaced the air filter on our furnace and suddenly started making this noise. When I remove the filter, it stops. When I close the filter case with no filter, still all good. When I put the filter back in, it starts making the noise after 15 or 20 seconds. We get the same filters delivered annually, so no changes there. Any ideas? It’s driving me crazy submitted by /u/badinnplaid [link] [comments]”

“I included a video (if you listen with headphones, especially like any ear buds that support spatial audio for 3D sound, that helps). It has a lower buzz/hum that travels far, coupled with a higher whine. This unit is about 3 years old, only used maybe 6 months out of the year, and has sounded like this for at least a year if not longer (maybe since the beginning, just don't remember). As you can see, it's on some kind of isolators. I've tried basic moving/nudging to see if it was an”

“My air handler’s drain line vent often makes popping sound during/after AC usage. The sound is not there when I’m not using the AC or if I’ve used the AC, it goes away within 30-60 minutes after turning off the AC. When the sound is there, there seems to be a negative pressure in the vent hole. If I plug the hole with a paper towel or my hand, the sound is essentially silenced. I was hoping someone could spot in the photos what could be causing it. The AC installer came a few days ago to take a”

“Help identify the buzzing sound. It happened around 5-6 days ago as well and was louder. submitted by /u/AnimalNo3310 [link] [comments]”

“We’ve been dealing with a persistent banging noise from our building’s HVAC system for more than a year . It has been affecting our unit significantly, including at night, and despite multiple investigations and contractor visits, the issue still hasn’t been resolved. Banging noise is obviously from the mechanical room, and our understanding is that since our unit and a couple of units above us are located close to the common wall where some of the main piping is located, we are the most impacte”

“I’ve lived in this home for a couple years now with no HVAC issues, this noise just started recently when the cooling system powers on. What is the possible issue? submitted by /u/GoHawks_121212 [link] [comments]”

“HVAC makes weird noises when the AC is on. This has been going on for a bit. Landlord had a tech look at it last year who wouldn’t say anything was wrong with it, but it is quite disruptive to sleep. Sometimes it goes repeatedly for a while, sometimes it stops, but it seems to only happen when the AC is on; I don’t remember it being an issue during the winter. Anyone have any thoughts on what could be causing it by the noise? submitted by /u/Sudden-Injury-4419 [link] [comments]”

“Video with sound of the AC on startup. The loud noise slowly fades away over 10-15 seconds. Guy came out and said the compressor is bad and with this unit it’s better to just throw the whole thing out and get a new install. This is a 2021, previous owner did not register it so I’m out of warranty. submitted by /u/MonstrousNuts [link] [comments]”

“Bought this new house, and the filter setup is different than anything Ive ever seen. To be fair though, I haven’t seen a lot. The airflow sucks the filter up like seen in the picture and there is nothing to block it / hold it in place. The filter fits and lays flat in that slot when the air isn’t running. Im assuming the filter being bent like this while the air is running isn’t good, so is their any fixes I can make? submitted by /u/ProfessionalRocket47 [link] [comments]”

“Hi, before I start, I know *some* noise is expected. But I don't think the noises coming from my units are expected. I've never heard anything like it. I've attached a video of it. I hear it whenever the compressor kicks in or turns off. It starts very loud and then even after it settles in I can still very clearly hear a gurgling/whooshing noise louder than the fan. It's annoying me because for something I hoped I'd be able to use at nighttime, I simply can't because it&”

“What’s causing this sound? My AC is currently very loud. It was installed in 2018 . I had them come back because it was loud. They installed a second return vent . Still loud. Lived with it being loud. But now it’s somehow even louder. They installed a compressor saver . It is still loud. submitted by /u/EitherWay-Lovely [link] [comments]”

“The handler & return units are located inside a bedroom in my house, and it coming off and on all night is definitely affecting sleep. The picture attached, the door is in the living space but the other side/jut out is in the bedroom. I don’t have a whistling in the grilles like I’ve heard described by some, it’s more just the unit coming on and the blowing noise that is very loud. submitted by /u/manyjoymany [link] [comments]”

“So we just moved in to a new apartment and this is the sound we hear when the AC is running. I filled out a maintenance report because I thought surely something was wrong. The AC tech they sent out said the fan was just close to the filter and nothing can be done? I dont know a thing about HVAC so just curious as to what any pros think. Thank you! submitted by /u/animalman422 [link] [comments]”

“I just had a 22 year old HVAC system fully replaced 8 weeks ago, the indoor and outdoor units, for $16,000. Since it was put in, I am hearing a constant loud gurgling sound and whooshing from the ground floor laundry room sink drain, which is directly below the HVAC upstairs. I am also hearing an occasional metallic thud noise in the wall. It’s loud enough to wake me up in my downstairs bedroom across the hall from the laundry room. I have recordings of the noises but Reddit isn’t allowing me to”

“Hi, I know very little about HVAC, so I apologize in advance for the poorly worded question. I recently got a new AC/furnace system installed to replace an old one. I'm downstairs in my house and the unit is on the other side of my wall in a closet. There is a cooling vent in my room leading directly from it. My issue is that whenever it is cooling, it's making a fairly quiet but very high pitched repeated and varied chirping noise. It's definitely only happening when it's coolin”

“Long story short I have had two different AC repair companies come out to look at my unit and neither of them can figure out why it randomly makes loud noises and or doesn't cool very well or at all. About two months ago randomly my ac unit fan/compressor started to act up. The first symptom we noticed was the compressor would start and it was VERY loud. When it made this noise it was still cooling the house but not very well. I should add that when I hear this noise the fan seems to be runn”

“my ac outdoor unit making some tiktik noise is this normal ? submitted by /u/BikeParticular416 [link] [comments]”

“What's this noise coming from our HVAC unit? Is it emergent? Can I run it still? submitted by /u/Bw0434 [link] [comments]”

“Our exterior HVAC unit has always been smooth sounding, for the most part, but after the big east coast heatwave we had over the July 4th weekend, it became much louder. We got the capacitor changed out last summer. The unit is about 10 years old, from what we can gather. We had a tech come out and he said that everything seems fine with it. It is still cooling the house normally. submitted by /u/BeezalTron [link] [comments]”

“AC wasn’t blowing cold air from vents. The air filter was very well used and needs replacement. I turned off thermostat and went outside and turned thermostat back on to cool and the condenser hummed but fan didn’t spin. I did this a couple times and one time I spun the fan manually and when it kicked back in fan was spinning but not delivering cool air. About 20 minutes later cold air now blowing. 1 - buying new filters now 2 - initial internet search was saying replace capacitor Does it sound”

“My unit (ELL Como 9000) has been making this strange repetitive rattly/crackly/rustly/buzzy sort of noise since day one. When I turn it on it's just the normal whir of the unit, but after a few minutes this repetitive sound starts up and continues until I change the mode (which causes it to judder) or until the unit is turned off. As this is my first AC, unfortunately I don't know if this noise is normal or not. I've contacted the manufacturer (no reply) and the retailer to ask about”

“Older house with an 8yo Carrier indoor unit, the outdoor unit is old but in good shape. Last week I noticed in the middle of the night that the main return register in the living room was louder than usual and not consistent. I would describe the sounds as turbulent air. Had our HVAC company come out and check it out. I had recently replaced the filter so that was ok. He went through and cleaned out the outside unit but didn’t notice anything. Just now I noticed it again and my wife thought the”

“Hello guys, is this a normal sound coming from an HVAC unit? The sound comes on every 24 seconds. We moved into this house 5 years ago so I’m not sure how old this unit is. The sound starts at 3 seconds. Location: Las Vegas Thank you in advance. submitted by /u/arnold188 [link] [comments]”

“Lennox system about a year old. Not sure when this started but noticed it in the last couple weeks. The first half of the video has the rattle then it fades and goes away. Seems like this behaviour goes on the entire time the system is running. If I had to guess maybe 20-30% of the time it's "rattling". Should I call a tech? EDIT TO ADD: there are no obvious loose screws, doesn't seem like the body rattling. No noticeable icing anywhere, fina seems very clean. submitted b”

“I'm not familiar with HVAC systems. Is the sound I hear from the condenser a typical sound during startup or should I have it checked out? If so, what could be the issue? submitted by /u/Full_Wrangler_2333 [link] [comments]”

“It’s been super hot as everyone know! I’ve had it set at 76F in the house. It still runs a lot! I just happened to notice it was making this sound today. Maybe I haven’t paid enough attention to it. It just sounded different than normal. Looking for help/reassurance that I’m not crazy. Thank you! submitted by /u/StWallCloud06 [link] [comments]”

“As title suggests , loud nois is coming out ? What could it be and how to fix it ? submitted by /u/NMALaw [link] [comments]”

“Any idea of what this sound could be coming from? It’s not all the time, very inconsistent. Clean filter and I don’t see anything loose inside the blower wheel house. submitted by /u/Alternative_Block230 [link] [comments]”

“The utility closet is in my bedroom and this thudding noise keeps waking me up at night or right when I'm about to fall asleep. Sometimes the AC turns on with a smooth whirring sound (kind of like an electric train accelerating?) but it's mostly this thudding noise. I hear the relay clicking which I understand is normal but I don't recall hearing this thudding noise at my last place. The unit is this: https://www.johnstonesupply.com/product-view?pID=B61-448 submitted by /”

“Does anybody know what this noise is coming from my condenser. It happens when the system is cycling on and off the noise does eventually stop is this something I should be worried about? submitted by /u/N591ER [link] [comments]”

“We have been having nonstop issues with our AC. Had the motor and squirrel cage fixed 6 months ago. I noticed it rattling months later. The same company fixed something else, I am forgetting now. And last week it wouldn't cool the house, the air was barely pushing through and everything froze over. We waited for it to thaw out. My husband cleaned away dust and debris and I told him to check if the filter was the right size (they replaced it). It wasn't. What should we check on now to pre”

“Before taking it apart, wondering what might be causing this annoying noise 😢. (note: NOT an hvac professional) submitted by /u/heatmiser333 [link] [comments]”

“I changed my air filter the other day and cleaned out my drain while I was at it. I’ve been doing this monthly or so for the last year, never had a problem. Ac will run for a few hours and then shut down due to high condensation level. The pan is full and dripping into my garage. I cleaned the drain again but still having issues. I went from a MERV 8 to a MERV 5. I don’t know if that has something to do with it. Any ideas would be appreciated. submitted by /u/1977john [link] [c”

“I recently, as in last week, had my condenser fan motor replaced because it was noisy and the new motor seems to be making a similar noise. I attached a video of the noise it makes when powers off and the fan winds down. Is this normal and should I call them back? submitted by /u/extreme_snothells [link] [comments]”

“Wondering if someone can help me with a problem I'm having with my AC I have a 12 year old Lennox unit that recently started making this loud buzzing sound when on. Sometimes the sound goes on when the unit is turned on and sometimes it doesn't. Sometimes it makes the sound and goes off and sometimes it makes the sound and doesn't go off until the unit shuts off. The unit is still blowing cold air inside the house. The AC fan usually turns normally, but in this video It looks like th”

“Included video for the sound! It was making spaceship noise (spinning sound?) What steps can I take to troubleshoot this? Thank you!!:( submitted by /u/frustratedwithwork10 [link] [comments]”

“I'm well aware that I should just call maintenance and wait forever for them to fix it, but it's quite annoying and I don't want to blow anything up by keeping the AC going. Outside sounds fine and runs the full time, but the (blower motor?) kicks on and off repeatedly each cycle and its making a loud hissing noise submitted by /u/Puzzled-External-573 [link] [comments]”