I can't say this would be the issue, but I do wonder if this is a result of the mounting bracket not being secured at all 4 corners. If there is any play at the bottom I could see it causing a problem. I have Fujitsu's an none of my 4 rattle, but I secured the heck out of the mounting bracket. Ionized, what do you think?

ajsmama, the mini-split will likely do the job, but for straight heat you should look at the Rinnai Energysaver. There are thousands of them installed in the Berks.

Thanks - my dad wouldn't be happy spending more $ on another heating system now that they finally put in the mini-splits (my mom wanted it in the summer for AC in the main part of the house, the only windows they have to put ACs in are in DR and BRs). No gas in rural area so would have to be propane.

But we might look into it (propane) for ourselves, if we had propane heat we could make due with small(er) generator just to run a few lights, fridge, and a 20A kitchen circuit in case of power outages.

I am sure that you have thought of it, but propane makes for a great generator fuel as well.

Yeah, but the whole-house propane/NG (not that we have gas here) generators are more expensive. And it would be more efficient to install a propane heater or 2 (was thinking FPs but will look at Rinnai) and get a smaller (LP or gasoline) generator than to run our GSHP (esp. in electrical strip heating mode) off a generator.

I think I've hijacked this thread enough, thanks for the info. I'll start a new thread if we start looking at propane.

If you look at the EX22, 8200-21,500btu it draws from 33-56 watts, so very efficient electrically. Modulating burner and blower, quiet and cool to the touch. What is FP?

Fireplace - my parents have wood-burning brick FP between picture window and sliding glass door if that's what you're wondering. Or my last post, I was referring to a propane fireplace, my uncle has one, we were thinking we could put tank on gable end of house and pipe straight up exterior to put one between windows in MBR, and could also go over (through basement, not wrapping around exterior) about 12ft to put one between a double hung window and our slider, where I had originally planned a woodburning stove to heat our open floorplan kitchen/FR/DR.

I just had a Fujitsu heat/air ductless system installed....I am heartsick....I spent so much money and now I have to contend with a constant clicking noise....it even makes this noise when it is off!!.....my contractor said it is from coils expanding and should "go away" in time.....I don't find this explanation acceptable....I don't know what to do from here....has anyone solved this problem....it is very annoying and it drives my dog crazy........

To bak2schultzie,

We have Fujitsu, 2 ceiling and 3 wall units. We have never had any clicking. Try calling Fujitsu and talking to technical support yourself. This is not normal.

My Mitsubishi are quiet as church mice unless you raise the blower speed to max.

Mines quiet to besides the usual plastic expanding and contracting from the heat. Since its been getting colder i can hear it ramp up but it not bad.

The intermittent clicking problem is caused by the sleeve bearing on the squirrel cage fan. The bearing is on the left side of the squirrel cage fan axel. It is a three part bearing mounted in a black rubber bushing. Either the entire bearing is bad (worn) or it just needs to be repacked with grease. The blades on the squirrel cage fan easily get caked up with dust which causes the fan to get out of balance and wobble a bit, making the clicking noise - usually on lower fan settings. The caking will happen very fast if you have pets due to hair. The bearing is easy to replace but you should have a qualified service tech do it unless you have very good mechanical ability. Cleaning the fan blades is a must, but not easy to do because it's in a tight space. Use a small soft brush like a bottle brush and clean each blade. Then blow it all out with a air compressor.

Trimtab21, I've read the service manual (Mitsubishi MSZ)l to see if taking the squirrel cage out to clean it is practical. The manual has instructions to remove a lot of other stuff first , electrical box cover, electrical box, PC board, motor, thermistor a "corner box" (that I have not been able to identify) and then line flow fan). Included in that is loosening the set screw for the line flow fan before removing the motor. It finishes with instruction to remove the screws holding the left side of the heat exchanger, lifting the heat exchanger and pulling out the cage. It seems to me that I should be able to just lift the left side and pull the cage out after loosening the set screw.

The manual does not have instructions for removing the drip tray for cleaning, but I've seen videos for other brands that indicate that it is simple. Do you have any tips for the MSZ?

Same problem here- all 3 of my Mitsubishi wall units make this awful popping/clicking noise. It sounds like they have zero solution for it. I am going straight to the manufacturer to try to get some of my money back. Tell everyone you know THINK TWICE before purchasing this system.

We have had our 3 Mitsubishi Mr. Slim units for 5 years now with no problems until now. one of the units is making an intermitant Popping/Crackling sound. we had our installer check it out and says it is from contraction which I find strange because it never made any of this sound until this year and the other units in the house dont make any noises, either. The other problems we have had with these units is small black particles falling to the floor from these units. The Mitsubishi Certified installer took the units a part and discovered a build-up of mold inside the units and this is what was the black particles that were falling from the units to the floor. We clean the filters every month so it seems like there isnt anything we can do to prevent this mold build-up.. i will follow this thread and hope others posts any disgnoses or solutions to these problems.

i would not be surprised to find that the noise comes from build-up on some part, probably the blower wheel. Mini splits seem to require quite a bit of maintenance, especially in dusty environments. Find this thread:

mini-split Achilles heel

Hi folks - original poster here, giving an update. We have not successfully solved the cracking issue, though it has gotten better with time. We have our Mr. Slim on the second floor (originally the attic) of a Cape Cod house, and it gets stuffy quickly. We have noticed that the cracking/popping noises are much worse when we turn on the AC function when it is cooler outside than in the room (it is possible for it to be 65 outside and for our room to be 78 inside). We have 'solved' the issue by anticipating when we will want the room cool, and turning the unit on an hour or two before using the room... that way, the unit seems to get most of it's cracking noises out of the way before we try to sleep.

We have also had the mold issues, despite vigilant cleaning. I had a tech come in at the end of last summer to clean the unit as the room was starting to smell moldy. He removed the blower assembly and cleaned and dried it as quickly as he could since we were paying him by the hour. $335 later, he suggested that we order an extra blower assembly and have them switched out seasonally. That way, we could clean and dry the 'used' assembly ourselves and save on labor costs in the long term.

Bottom line: I *think* we would buy our Mr. Slim unit again, but I would not recommend it to others. We purchased it only because we needed a second zone in our house and could not fit a traditional HVAC unit in the space available. Should we ever bump out or expand the top floor of our home, we would replace the Mr. Slim with a second HVAC unit. If you are on a budget and looking to zone a room in your home, I would go with an old fashioned window unit in the summer and a space heater in the winter.

Hi, moraflauta. Did you watch the cleaning happening? If so, did the tech remove the motor and do a lot of other stuff on the right side or just make the coil loose and slide out the blower cage from the left like in the video referenced below? Did he remove the drain pan and clean that out and flush out the drain tube with disinfecting cleaner?

https://www.youtube.com/watch?v=OiEcHHzz8YU#t=130.2113363

My recollection: he removed and cleaned the blower wheel. That is the part that he suggested we order and switch out when the next cleaning is needed. I don't recall that he removed the drain pan, etc. We will order a new blower wheel later this summer. Thanks for the info - I will ask the tech to remove and clean the drain pan and drain tube when the new blower wheel gets installed.

Have you read this thread in this forum?

"mini-split Achilles heel"

ionized - Nope! I got back on this thread because Houzz let me know that Gayle had sent in a question, and I thought I would follow up. I punched "mini-split Achilles heel" into the search function, and am not finding anything. Without reading the thread, I would agree that mini-splits do require a lot more maintenance than the manual suggests. Actually, the routine maintenance provided does not keep mold and cracking issues from happening, and we have also had issues with finding techs who can properly service the unit (for example, the last one did nothing with the drain pan, etc.). I would like to think that our room is not overly dusty, and I clean the filters every two weeks when the unit is running (we do not use it in the cold weather). However, since the split is over 6 feet off the ground, perhaps the area accumulates more dust than we realize. An additional bottom line: these things are a pain to maintain and it is difficult to find people who can service them (for those of us who are not HVAC savvy).

I searched on Samsung mini-split noise and came here..I have a 17000 btu Samsung Inverter mini-split. It's under warranty right now. I noticed the "popping" soon after they installed. I went straight to the Samsung Service Center, and they sent a team out. They said "bad evap." Came a week later with the part, and they took the blower apart, but said basically, the installer had not tightened a nut enough, therefore pressure wasn't high enough....so they replaced the part, topped up and checked pressure...said part wasn't needed, but they replaced it. I live in Thailand, and the a/c season is long. April is the hottest month with temps near 107F. The thing cools beautifully, and its electric use is minimal...I just paid a 31 day electric bill that was 290 units or 1 usd per day. I use the thing almost 24/7. But, that damn popping noise aggravates the shiite out of me...not really because of the noise, but because of bad engineering. The fan is more quiet than a basic wall fan...so it's not the bearings. I read all the comments...and the one that seems to be on the money is that the popping noise is worse, when it could even be cooler outside than in. If it is really hot outside, it doesn't pop at all. But, lately, with the rainy season, we can get much cooler temps (75-79), and the thing is barely working, but the dehumidification is really needed. I also notice it's worse on "auto" which is an energy saving feature. Funny thing is that Mitsu has a much better reputation than Samsung, and the popping is my only regret about Samsung. Mitsu is quite a bit more here, especially Mr. Slim. Mine was 795 usd, installed...inverter, 410a system, no heat. Probably 2000 less than you all paid. But still, I hate short cuts and bad engineering. I plan on talking to the Service Center again. I appreciate everyone's contributions. Expansion/contraction is a big part of it...and there is a switch inside the main board box..that could play into it. I've stayed plenty cool all year, but would like to nip this thing in the bud before the warrant expires..and it is loud enough to wake you up, but so are the neighbors slamming their doors and the 50 jets taking off per day at the local airport.

We had 4 Mitsubishi units installed in 4 new rooms September. All 4 make the clicking/popping sound. It wakes us up in the night. Does anyone know specifically what is causing the snap/crackle pop? I noticed that our bedroom unit clicks/pops even when it is off. I am wondering if we are hearing sound travelling from the bathroom unit (which is on) travelling behind the wall and out of the bedroom unit? Or are the copper refrigerant lines that carry the Freon to/from the bedroom unit actually expanding/contracting at the unit because Freon is circulating through the bedroom unit even when it is off?

Well, mini-splits shouldn't make this noise so there's a problem with either the equipment or the installation. Get the installer back to fix it.

Been there done that.... thus why I started this thread and I imagine others joined in: the installers were never able to fix the issue. We sold the house, so it is no longer a concern. Best of luck to current owners who are dealing with noise problems on these units.

I've never noticed any noise like that with my MSZ-GE0... units.

My wife and I put 2 Mr Slims upstairs in our house for A/C mostly but were talked into getting both A/C and heat. We had good luck with the A/C but using them this Nov. on heat we noticed right away this cracking/clicking noise as well. I have read all the comments and I think I will call Mitsubishi to see what they might have to say. Its annoying trying to sleep with the noises. It's very noticeable in a quiet room.

Lots of good info here but not convinced anyone has the answer yet. Sounds like expansion contraction and plastic snapping but hard to pinpoint.

I will continue to monitor this thread in case someone gets a definitive answer.

I will post if I find anything out.

Following. Same issues here.

I have same noise/clicking issue with my Mr Slim, I think its the plastic of the clap making that noise. Went up there and touched the clap/door who covers the filters and its pretty hot, set at 22c. Turned the unit off, cracking noise for 7-8 minutes and now...ahhh silence. Think the plastic is not resistant to temperature hot or cold, seams i'd makes that noise in summer too. Have that unit for 15 mouths, cleaned the filters as prescribed and I'm pretty upset to read in this tread that is it a commun problem. I dont think the repair company can do anything except charging me for coming see and clean it even if it won't change anything. It seam to me its a fabrication default. reading on their pages 5 years warranty on pieces, i'll contact the reseller but I am not happy Mitsubishi.

following

Following

I purchased Mitsubishi ductless heat pump system in December. My bedroom units have been making the popping/cracking noises and I have not slept a full night in 5 months! It has been horrible! I have worked with my installer who basically says nothing is wrong and this is expansion and contraction noise which is noted in the owners manual. However, I did not get my owners manual until I paid teh $12,000 to install and purchase! I am so upset, I cannot even heat my house at night. I turn all units off completely so I can sleep. Not sure what to do at this point. DO NOT BUY THESE UNITS! Anyone have advice? Thanks!

I just completed my second hot season with my Samsung, 17000 BTU....31 day electric bill was 27.40 USD....at times it was too cold in here with the thermostat on 26 Celsius, 78.8F.....still makes those darn noises...but I will stand by what I said last year and that is that it is perfectly quiet when it is blazing hot out, but the noises start when it gets much cooler outside, and that is usually going to be 3 or 4 am when you are sleeping. Run it cooler (cost pennies to run), then shut it off late at night, or use the timer. Contraction and expansion ....bad engineering, but seems to be working great. Outside unit is super quiet and seems like it is not straining at all. At least there are nobig bangs at start up, like the old units.

I was having the same problem with excessive noises and clicking. What I realized was that the wall and the mounting bracket were both bent. I live in a log cabin, the walls are not flat at all. I even asked the installers if it would be a problem, and they said no, because they first attach a mounting bracket to the wall. Well, the mounting bracket is a fairly thin piece of metal. If you screw it to a curved surface, it curves too. To fix it, I took the unit off the bracket and supported it on a ladder. It was impossible to move it far away because of the lines going through the wall. I then took the screws out of the mounting bracket, placed shims behind the bracket, and replaced the screws. This straightened out and plumbed the mounting bracket, and the excessive popping has been greatly reduced.

Like mark says, the problem was the worst on cooler nights. I think this is because the unit doesn't continuously pump coolant through the coils, but rather cycles on and off. This causes the coils to expand and contract. Before I fixed mine, I would get cycles of about a minute of loud pops, occurring every few seconds, and then a few minutes of silence. Now I get only a quiet pop or two, regardless of outside temp. It's quiet enough now I don't notice or think about it anymore.

Lastly, this was a real pain to do. It is difficult to work behind the unit, difficult to remove it from the bracket, and even harder to replace it. Get at least one other person to help out.

Just for general interest . You can buy special harnesses or slings to hold minisplits while they're being worked on . I'm not certain it would be useful in this case because they might actually hook to the existing bracket. I have not analyzed exactly how they work . They might be worth looking into it somebody has to do a lot of this stuff.. I repositioned one of my brackets with just my two hands, no fun . When looking at a log wall, or some other similar problem, it is clear that anchoring a stout piece of plywood on the wall first would be the best way to go.

Last month we had a 18,000 btu Carrier High Wall mini split system installed in our master bedroom. We like to sleep cold, and it replaced a window unit that supplemented our whole house central a/c heatpump. Since it was installed, it cools great but makes these intermittent popping noises, sometimes followed by crackling. Some of the popping is loud, sometimes light, but it wakes me up all night and is very annoying. It does not stop as long as the unit is running. My husband even notices it, and he sleeps really deep. I had my installer come out a week after install, and he claims he doesn't hear anything. I called him again and he acts like I'm crazy. Seriously, there is no way it can be a normal sound! We have slept in the same room with several mini splits and they are super quiet, which is why we went to the expense of replacing the window a/c. Reviews on the Carrier site all say super quiet, ours definitely is not - we are very disappointed. Advice?

An 18 is WAY oversized for a normal sized bedroom. How many sq ft? Did you spec this unit of the contractor? It sounds like you replaced an 18 window shaker with an 18 mini split. Yes? If so you have a unit that is probably twice as efficient as the old WS and oversized. I think what is happening is that your unit is in fact unable to operate at the lowest setting for the 18. What I mean there is that it is so oversized that even at the minimum it is reaching the set temp and must shut down. As it shuts down pressures and temps equalize within the unit you are getting expansion and contraction noise internal to the unit, and possibly from the dealer installed lineset which feeds the refrigerant to the indoor unit. What is the minimum input for your model? Sq ft, minimum and was it an 18 for 18?

Also, please understand, that with variable speed or modulating equipment, in my experience the low input is more important than the high in your comfort. Most folks think bigger is better in heating and AC. That wasn’t correct even when all equipment was either on or off at max input. I have a 12000 in my bedroom. It is oversized, but the low input is 3200 BTU’s. The unit runs almost all the time on low, but in our hot CA nights, once it cools the space, it simply runs in the very low ranges and we are comfortable all night long. Mini-splits are fabulous technology but they must be properly understood to select the correct unit and get the comfort you deserve out of them.

as far as oversizing....seems that several of us have noticed the noise was worse when it became cooler at night, and just barely needed ac, if at all. 18000 is pretty much the standard here for studio condos, which are about 230 st of space to be cooled. The guidelines say that will work for 180-280 sf, but factors can also be ceiling height, exposure, and floor. I sold the place with the Samsung...funny thing is, the place I bought has a 15 yo Mitsu/Fuji system that I valued at zero when offering on the new place. But, I am about a mile away from the headquarters of a major Thai brand and manufacturer, and there is a Carrier dealer down the street. But if the 10 homes I have bought....this old Mitsu is the best one I have ever gotten with a used home..lol. A new system would save me 10 us per month, max...but if I got a dud, it would be a nightmare....so going to get a few years out of this one. Been using the timer, so it shuts off about 4am....and also using the fan on low...and a wall fan On the opposite wall..also on low...78 would be freezing....Interesting g topic..best wishes to everyone!

Thank you all for your very helpful responses. My bill from my contractor said 18,000 btu but my husband checked the Model info on the unit outside and it is actually a 12,000 btu unit, which is what we talked about beforehand. Room is 15x18 with 10' ceilings, modern construction with good insulation. Very hot 100+ Texas summer days, only cooling outside to the 80's at night. Entire house is kept at constant 72 degrees, all we want it for is to cool our bedroom down to 66-68 at night. Our bedroom is the warmest room in the house, with 4 large windows, but obviously it doesn't have to work very hard. We do shut the door at night. You are right, it is a lot more efficient and removes more moisture and feels colder - our window unit was set at 64 and we still felt hot sometimes. He is coming tomorrow to "listen to the noise". It does sound like expansion/contraction noises to me rather than something hitting anything, or it could be electrical. He told me it is 115volt. I just hope he doesn't say he can't hear anything wrong.

One other thing I talked to him about was the inside fan unit is not level at all, bubble on the level is not even in the middle marking. He said it had to be that way to drain, is this true or was it just sloppy install?

AC guy showed up this morning, and I had recorded on my phone the sound in case it didn't happen while he was there. He did hear the popping noise while he was there, it makes the noise when the outside unit cycles on and off. He confirmed it was an issue with the unit and was ordering a new one. So, be persistent if you have issues right away, hopefully this will correct the problem. Thanks for all your help!

I have 3 Mitsubishi units in my home and they all make a cracking sound like plastic rubbing together. The bizarre thing is that one of the units that I have downstairs makes noise even when the unit has been shut off for hours. For what these units cost I think that this is totally unacceptable

I have this problem with a new Mitsubishi system. I've been recording hours of sound at night and here is my comparison with sound samples:

https://docs.google.com/document/d/1RPORiBJO78Wp5gdoq18n26rOHnsLCMKxL4UBUoOBADg/edit?usp=sharing

I guess since they are new it's not the squirrel cage fan or whatever, but probably bent walls or something since the house is old. It's the only thing I can find so far that explains the variability across the different rooms.

@tbkjunk would provide any more info on how you shimmed it?

@tbkjunk yes, please share some more info on how you fixed this. I had my 2 Mitsu units installed and they keep making these noises. It's an old building, the walls are off.

The short answer is DONTBUYMITSUBSHI. I have 3 units 1 ductless and 2 ducted. 6 years have gone by and I have had trouble with all of them..where do I start,? Replaced coils on two of them one compresser shot..two housings on the ductless cracked and leaking condensate water.

Reliability? NO SIR. Junk! If your coils leak,it attacks the plastic housing and you are screwed!

Did the author of the original post ever solve the issues? we are having the identical problem. The clicking is drriving me crazy.

I rent an apartment that is heated/air conditioned by a Mitsubishi wall mounted unit with two pumps installed on the outside wall of my bedroom. Last year, I didn't seem to recall having any problems, but since winter set in, this year, there have been periods of excessive humming noise and vibration so that I could not sleep. Then a couple of weeks ago, during a snowstorm, water came through the ceiling unit in my living room. It ceased rather quickly once I shut down the unit. Interestingly enough, the outside noise and vibration seemed to have quietened down until a week or so ago. My landlord checked and confirmed that he heard the noise outside my window, and called a service technician, who came today. Low and behold, nice and quiet, no issues. I told him it was intermittent, but the company doesn't really deal with Mitsubishi so the representative couldn't offer an explanation, just suggested to tape record it when the noise happens again. I am not crazy or oversensitive. As a matter of fact, I have severe hearing impairment in one ear and cannot hear the alarm go off if I am lying on that side. Yet, for nights and days and weeks, the noise and vibration was so intense I couldn't sleep or concentrate on any activity. Has anyone else had this problem?

Same here! Expansion/contraction popping/cracking sounds. We just had two Mitsubishi split units installed. HVAC guy talked us out of installing a full system as part of our remodel because these were so good. They are 'contacting the rep' to understand what can be done. Funny, we stayed at a rental before moving back into our home and no cracking/popping sounds so there has got to be a solution out there. @tbkjunk I'd also be interested in details on your shimming solution. Because of the sound, our units are unuseable at night.

We we were able to temporarily solve this problem. The installer came out a couple of times to address this. It would help for awhile and later start making the noise again.

We had mold issues that were only temporarily solved, too. We paid a lot of money for these units and had continuous mold problems which cost more money to fix.

We have moved and would never purchase or recommend Mitsubishi units, again.

I hope you are able to permanently solve your crackling noise issue.

I have a solution. Now, this is an old old thread that has gotten a bit off-topic at times, with people reporting different issues, but the way I understand it is that this thread is about popping/cracking sounds that occur on the mini-split wall unit itself due to expansion and contraction of the plastic housing or other plastic parts. If you’ve read the thread, you’ll notice many others have reported the same problem, some achieving frustration levels to the point of pure purchase regret and recommendation that no one else buy a Mitsubishi heat pump. But so far none of the responses have offered a real solution to that particular problem.

Well, recently I noticed that the Mitsubishi mini-split in our bedroom was waking me up with these popping/cracking noises in the middle of the night. I finally remembered to look it up a few days ago, and I found this thread. It got me thinking - the noises must be coming from the joints between the plastic parts that are held together by clips or screws but can still move slightly against each other in places. When different parts expand or contract at different rates, and they can rub together, they make noise. Clean plastic of certain kinds has a tendency to stick and release when rubbing together, making noise - you can hear it if you grab the housing and lightly twist or flex it with your hands. But if you lube it up a bit, it glides smoothly and doesn’t make noise.

Solution: I went and got some silicone grease. I removed the housing and disassembled the unit as far as needed to get the cylinder fan out (many good YouTube videos about this - needs to be done occasionally for normal cleaning and maintenance anyway). I removed a couple more screws holding plastic parts together on the right side and flexed things around with my hands, listening for creaking and cracking noises. I put some silicone grease on a Q-tip and swabbed it as far into the joints as I could from different angles, and kept flexing it to work it in. As I continued to flex the parts, they got quieter. Then as I reassembled the unit, I put more silicone grease on all the edges and faces of the plastic parts that would touch other parts, making sure to put it on both sides. I greased up the plastic clips on the upper housing, the plastic pegs that hold the lower grill in position, the screw tabs and even the screws themselves before screwing them back together. I greased up the entire edge of the main housing and the wall mount it matches up with when installed. I wasn’t sure exactly where the operational cracking noises were coming from, so I tried hard to grease everything up to make sure I got the culprit.

Once I got it all back together and turned it on, it has been blissfully silent ever since! Two nights now of no cracking or popping. So if that’s your problem, I think this is your solution. If you don’t wanna do it yourself, get your HVAC service tech to do it when they service the unit next time. Hopefully this will help many people get a good night’s sleep and give Mitsubishi a break for what is an annoying but understandable problem with an otherwise fantastic heat pump system.