Mini Split Air Conditioner Leaking from the Indoor Unit.

June 16, 2010 by Shawn Mack  
Filed under Ask Thomas

First Name:  Eric

Last Initial:  B

Equipment:  Mitsubishi Mini Split Air Conditioner


The mini split AC unit cools beautifully.  However, anytime we set the temperature below 70 degrees, we will get water dripping from the inside unit.  This is not condensation water dripping from the vents - it is water coming out from the unit.  This unit does have a drain tube to the outside and it does work properly.  Could this water problem simply be a result of the drainage tube freezing?  If so, is there a solution.  It defeats the purpose of the AC unit if you cannot make it cool in the house.  Any responses are appreciated.


There are two possible solutions to prevent leaking from a mini split air conditioner indoor unit.  One:  There is a blockage in the drain line or the drain line is not installed properly and gravity cannot rid the system of the condensation build up.  Two:  The drain pan inside the indoor unit is level and water cannot drain, via gravity, out the back of the system and down the drain line.  Most units will need to be installed with a slight declination towards the drain line side.  This lets the water flow downward and out of your conditioned area.  People see leaking indoor units on very humid days when the drain pan fills more quickly and cannot terminate the water fast enough because of the drain pan being level.  I tell my customers to tilt the indoor system 1/8″ down towards the drain line at the time of installation.


92 Responses to “Mini Split Air Conditioner Leaking from the Indoor Unit.”
  1. Nick S. Says:

    I have a similar problem, but it is not related to either solution. (A/C temperature set to 70*) Condensate line is working properly. I noticed water droplets dripping from behind the fan inside the main unit. I was able to get an automotive telescopic mirror up inside and behind the fan (duct) and I could see part of the evaporator exposed.

    I live in Orlando and it seems to be very hot and humid this season. Obviously, the water condensing on the evaporator is not draining fast enough and some water is dripping straight down in to the fan duct. Any suggestions to a solution?

  2. Reeves Says:

    Thanks so much for this. I had no idea about the drain pan so, when mine started leaking I was freaking out. Cleaning the filters then tilting the drain pan worked a charm and it only took 20 minutes. Saved me calling my maintenance guy :)

  3. Dan Says:

    To Nick S. :

    I have the exact same problem with my Ramsond indoor unit. The condensation is coming from somewhere behind the fan and trickles down to the front of the unit where it drips out and onto the floor. The drain pan and tube appear to work properly as the condensation in the pan never overflows. The problem does seem worse on hotter and more humid days but it is so bad that I really cannot use the unit. I will be contacting the manufacturer today to see what can be done.

  4. Rachel Says:

    Dan– We have a Mitsubishi minisplit unit that is doing the same thing. The drain is working and no water builds up in the tray. But the unit is basically unusable because of all the water that is leaking out. We’ve had the unit installed and working beautifully for 3 months (and it’s been 90 degrees and humid most of that time) until this just happened. Have you come upon any solutions? Company tech support has thus far been unable to suggest a solution.

  5. Jason Says:

    I have an LG split unit ac that is maybe two months old. The unit is slanted to drain and the drain works. Im getting an oily substance on my wall thats definately not water and when i pop the bottom up to check it there is oily stuff on the lip underneath for the left two thirds of the unit. It drains on the left. I would appreciate any advice.

  6. Aaron Says:

    Jason, I have the same issue with a Sanyo, as well as the water issue that everyone else here has written about. The oily substance my AC guy said, “it’s just from fat and stuff in the air from the kitchen that gets pulled into the unit.” I’m not buying it. The oily substance is on the vent lip underneath, and I actually get specs of dirt and stuff under the unit. It has been installed seven years. The oil has been present for the last three or so, and the water all over my lamp and couch started today. It has been damp here lately, but I’m shocked that this unit could basically just pour enough water out of itself over a day that it drenched my lampshade and couch. No idea what to do next.

  7. Ben Says:

    I have had the same issue. It turns out that the refrigerant in the unit was very low. After having a friend who is a tech come out and look at the unit it was determined it needed 2 pounds. The system holds 4.6 pounds. Once done, no more condensation.

  8. Chris D Says:

    I have an LG mini split in basement. Have been experiencing some leakage from the middle of the unit inside my room when unit has been running for 2 hours. It seems to be draining fine with no blockage. Originally leaked out of the left side of unit (when facing unit). Readjusted and hasn’t dripped from either side except the middle. Had all the lines reinsulated as the refrigerant lines run through a crawl space that has been conditioned. Still humidity in basement but nowhere near the outside. Plus I have a dehumidifier in crawl. It seems that the leak is coming from the middle where the tubes for refrigerant enter the unit. Any suggestions?

  9. Sal Says:

    I have a similar problem with a Mr. Slim unit. The drain pan fills at times AND have had to have it recharged three times. It turned out that there was a leak in the evaporator coil as well as at the connections to the line set.
    Unfortunately for me, Mitsubishi will not honor the warranty because it was installed before July 4, 2008. The newer units carry a 5 year warranty. I don’t consider 4 years of use to be a normal situation.

  10. dave Says:

    anyone getting an oily substance runningg down their walls should call the installers immediately. this oily substance is in the coolant lines. this means your fittings are not tight and you are losing your coolant. They should tighten all line connections and recharge your coolant. Do not let them leave until they recharge your coolant.

  11. Anonymous Says:

    How do you find the drain pan? I can’t get to anything but the filter on mine. Granted it’s Multiline not Mitsubishi…but if any of you can tell how you got to your drain pan, mine’s got to be similar…

  12. Carola Says:

    We have a Fijitsu split air unit here in PR it stated leaking water like crazy yesterday, how do I check the drain hose or pipe?

  13. Victor Says:

    Hey Guys, the indoor unit had just leaking now. I open unit cover and found a small water container. It was open top container. Maybe it design like that to spill the water if it gets full.

    I thought it was because dirty drainese but then i found a corrosion rust chip and thought that the chip was blocking on the middle of the container because the left water level on container was different with the right water level on drain gate.

    So I put some hose on the left and blow it until all the rust chip that get stuck going out to the drain out gate.

    After that, it is not leak again.

  14. Mair Says:

    Most of the leakage happen to do something with the drainage or the duct. Also, there are some other possibilities too.

  15. Joe Says:

    I had a similar problem SOLVED today by the HVAC contractor that installed the units. I have a 4-unit Mitsubishi mini-split “Mr. Slim” (6-6-9-12) with a 36K compressor on my roof. The unit in the master bedroom worked fine all winter as a heater, but started leaking the 1st day I used it for the A/C. Apparently, there were TWO issues contributing to the water leaking into the house. First, the corrugated flexible drain line was no longer level when the unit was hung on the wall. The little hump made it harder for the water to drain by gravity. Second, since this was a relatively long drain line, I had something analogous to vapor lock, where their was negative pressure preventing the water from draining. Adjusting the flexible hose and installing an upside down “T” that allowed fresh air into the drain tube solved both problems. Now, the unit runs perfectly.

  16. troy Says:

    i had a similar problem with my 1.5 ton trane mini split system, the indoor unit sweating all night and all day. how can i solve it? will the desicant is a solution

  17. Ajay Says:

    Hi Guys, i am a HVAC Engineer. My answer for you guys:
    The indoor part of a domestic split A/C essentially consists of cooling coils and a blower fan. Air from the room is pulled over cold coils and the air is cooled. Colder air can hold less humidity than warm air, so water vapour condenses as liquid on the coils. The cold, dry air is blown back into the room.

    Meanwhile, the water on the coils drips on to a gutter or drip tray. This has an outlet which typically connects to a pipe on or inside the wall, and the water drains to the domestic drainage or else to outside. The A/C drips water when the drip tray is full, normally because of a blocked outlet.

    The solution is to remove the A/C case and clean out the drip tray and outlet. Owners’ manuals usually say to leave this to an appropriately qualified technician.

    As for prevention, the air inlet of a split unit includes filters to trap dust. It is this dust that finds its way on to the coils and gets washed into the drip tray by the condensing water. Keeping the air filters clean should decrease the amount of dust that gets on to the coils and therefore increase the period between sessions of cleaning out the drip tray.


  18. JoAnn Says:

    I am so happy I found this site. I have a Mitsubishi Mr Slim. It is leaking from the bottom of the OUTSIDE fan unit besides the normal drips of water coming from the overflow pipe but my concern is WHY is water dripping out from the bottom of the outside unit itself? Thanks so much. You give some great advice. Also, any recommendations for annual servicing of Mr Slim?

  19. Loyd the Contractor Says:

    I have 4 Migsubishi Mr Slims, within two weeks of turning them on for the first time two of the four started leaking down the wall from the backside, then down the front vanes onto the wall and floor (new floors). Then one stopped cooling all together. Then strangely enough the one that would not cool at first …. froze up with ice covering all the coils and then froze thewater in the drain pan completely. Considering the number of leaks reported on this blog and several others that I read, this is sadly a shocking common occurrence and therefor defect in the design. You simply don’t k ow what the heck is going to go wrong next. I have poured over a gallon of water in the drain line and the water drains just fine, so it is Not an issue of the drain pan. Issues such as ambient humidity should if designed well have nothing to do with it because half the excessive heat zones in our country experience high humidity during heat waves … lime almost the entire state of Florida and much of the coastal south. If the coil board and drain pan freeze up completely as mine did … It’s a design flaw. Yes you must keep the proper charge of refrigerant levels maxed out …. But put it this way, if your unit is clean, and you drain lines runs correctly, and your unit is luring out water, you have a defective unit, which is shockingly all too common especially considering the cost. I have a mitsubishi appointed technician coming over today. I’ll post what he has to say, but I will demand a new set of units. I’m tired of reading the multitude of ‘potential’ issues that go wrong and the numerous and uncertain remedies …. They are simply designed poorly and the public should know. Hopefully Mitsubishi will honor their warrantees even if it means replacement.

  20. Will from NY Says:

    I had two Mr. Slims that leaked within a month and one that is working fine on the same floor of the same home, so obviously it is not a high humidity issue. I also poured water from two full teapots down the drain pan on all three and they also all drained properly, so it was not the drainage line either. So no humidity or drainage problems were the cause. These units are so full of wires and thermostats and unbelievably fragile parts, just remove the plastic cover and you’ll be very disappointed at the fragile nature of the thin plastic mounts and general design. The area where the wiring board is next to the the on off are hardly attached to the unit itself with the thinnest plastic clip on tongues that I have ever seen on units this expensive. The science behind an air is not complex. The Mitsubishi tech that came out told me that he has had to deal with these leaking issues on almost half the units he installed, and he no longer recommends them. Luckily for me, he also told me that Mitsubishi is well aware of the problem and has claimed to have fixed the design flaws in their most recent units. My technician said the only correct thing to do was to replace the unit for free, he took the defective units and sent them back to Mitsubishi. You should insist on a new replacement unit at no cost, and then sit back, keep your fingers crossed, and hope it gives you a few years before something else that shouldn’t go wrong does go wrong. So much for a unit that works for a few weeks them malfunctions causing property damage to the floors and walls … The property owner becomes a three time loser, you’re afraid to turn the unit on when it’s hot due to the leak, so you’re boiling, you over paid for a unit that corporate Mitsubishi is aware of but happily sells to you anyway, and everyone including their Aunt Emma can’t get an honest answer to the problems. Luckily, I was sent an honest technician and I got replacement units, but the odds are very low that you will. Most technicians don’t really give a damn, and they are afraid to send back a unit(s) to Mitsubishi for fear of a bit of paperwork and the time it takes to complete their report to Mitsubishi.

  21. Jimmy D Says:

    My Klimaire 2 ton minisplit works beautifully. The drain works beautifully. About a week ago water started dripping from the bottom of the indoor unit. It appears that the refrigerant line coming into the unit gets cold and condensation forms. The line is wrapped with a sponge type pipe insulation and the condensed water pooled inside the insulation and then started dripping. Why does the line start sweating now as opposed to the last trouble free year and a half of operation? Is the line colder now than it used to be? Is this a result of refrigerant getting low? Nothing has changed since I installed it. Now I can turn the unit on and watch the water condense and start dripping off the line. Anyone know why this is?

  22. Eric A Says:

    Having the same problems as Jimmy D on Mr. Slim. Would like to know if there is something else I should be concerned about before I cut off the factory installed insulation and put my own on. Thanks.

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  24. Tracy Says:

    I was about to purchase a mini-split for a new large addition game-room with new carpet. Hearing all this stuff scares me. I really did NOT want a window unit (as most here prob did not either), but I’m thinking now that I should save some money & aggravation and purchase a traditional window unit instead of a mini-split. Thanks for the information! - tracy

  25. elifepharmacy Says:

    Thanks so much for this.

  26. Steve Metcalf Says:

    Just had a 3 ton Mitsubishi Mr. Slim and a seperate 1 ton Mr. Split installed in a new addition on my house. The first warm day I ran the 1 ton there was about a half a gallon of water on the floor, I thought maybe I was overworking the one ton unit, turned the 3 ton on also looked 2 hours later & all of the units are dripping water on the floor & on my furniture.
    I checked the drains all clear, These things are very expensive & I trust Mitsubishi as a manufacturer of high quality electronics. I’ll call my a/c guy Monday and have him come out & check it. I hope I can count on Mitsubishi to make this right. Man I am not happy.

  27. Darrell Snuffer Says:

    My Klimaire 2 ton minisplit has started iceing over in the air handler. I also have the same problem with water drip. Any having an answer for the ice. thanks, Darrell

  28. steve metcalf Says:

    I purchased a 1 ton with one inside unit and a 3 ton with 3 inside units for my 1500sf foam insulated addition, had them professionally installed & the first humid day all 4 inside units are drip dripping water on the floor, with some splashing on the wall.
    I spent a lot of time carefully placing drain tubes so they only go down hill in the walls so after the drywall work was done my a/c guy would have an easy time connecting the drains.
    This was new construction so the lines & wiring are hidden in the walls & the attic (also fully foam insulated from the underside of the roof down)
    Of course it did not drip until the temprature & humidity increased this summer so it was not fixed last year.
    Now I wish I would have just installed a traditional heat pump with duct work, less frustration, expense & work.
    I’m very frustrated.

  29. Terry Says:

    We just ordered a 1 ton Mitsubishi and now concerned after reading the message boards. Mitsubishi is highly recommended over the other brands. We were going to mount ours up high on an outside wall and have our TV on the same wall. Not sure what to do now?

  30. dominic Says:

    i purchased a dual mini spilt system, unit A is a 12000 btu unit B is a 9000 btu my problem is unit B i working fine blowing cold air, unit A is blowing room temperature air, could one of the coils on unit A be cloged

  31. Ann Says:

    We had “traditional” central air installed on the second floor of our home; ducts in attic. The installer advised us to install a ductless split on the first floor to avoid ducts in basement and floor vents — what a mistake. The system (LG) has been trouble from the second year of usage. Quality furniture has been damaged from water runoff. Tonight it happened again - thank goodness, my dog alerted me by running over to the pool of water forming on the floor. We had a huge mess to clean up yet again.

    It has been virtually impossible to reach “customer service” for assistance…very disappointing.

    I have spoken with colleagues who seem pleased with their air conditioners (not sure which brands), but I would advise potential buyers to think twice.

  32. Kellygirl Says:

    I have a Fijutsu hybrid mini split (Halcyon) and there is clear oil dripping from the bottom of the inside unit. Does anyone know what this could be and should I turn off the unit while I figure out what it is and get it fixed?

  33. Wyogirl Says:

    Wish we had seen this blog before we bought our mini split. Leaked from day one. We’ve tried everything mentioned, drain line etc. still have leakage. Our rug is ruined, and we’re worried about the floor underneath.

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  35. Donna K. Says:

    We have a Sanyo mini split, that’s going on it’s 3rd Summer. Last year we atarted to see a cloud of vapor come from the unit into our living room. Husband took air compressor and blew it out best as he could. Our installer is retired and nobody in this small town wants to deal with these units. So last year we road on luck and it worked without vapor. This season though, it was again cleaned and was working well. But, just today, I was in the kitchen and turned around to see the vaport cloud once again. Please, what really is the cause? I’ve tried various settings and seeing this cloud makes me think I’m doing something wrong just running it !

  36. AC Key Says:

    I have had my Mitsubishi Mr. Slim large living room unit for 7 years. I live in the FL Keys where temps in August are in the 90’s. The first time I experience dripping on the inside was about 2 years ago with the master (med. size) unit. I called the local tech (who hates working on these systems, because he cannot access all areas of the inside unit. The outside he doesn’t mind, but the parts are expensive.) He didn’t do anything I couldn’t have done myself, and I am 65 yrs. Last night, the living room unit (I have 3 down and 2 new ones upstairs), started dripping on my sofa where I was sitting. I put a towel there, turned the unit off, and turned the other 2 to 75 degrees with half fan and doors from the bedrooms open. I slept at a comfortable temperature all night. This morning I turned the 2 in the bedrooms back to 78 degrees and turned the living room back on at 78 as well. I think the coils freeze up with the drain, and the water has nowhere to go but out on the more open side. The unit is working fine today. Hope this helps.

  37. Wally Schauer Says:

    I installed a 2 ton LG split unit a few month ago also. (I used to run a 100 ton refrigeration plant for a juice company, so yes, it is installed right). It also has the condensate problems from the indoor unit. I have opened the filter doors while its operating and found the condensate running down from the coils onto the plastic framework that touches the coils, and on down out the front. I have used small (1/4″ thick blocks of hard foam rubber to keep the framework from touching the coils, and this helped probably 50 percent. I also have been experimenting with the temp and fan speed like AC Key says in his comments. It will have the heaviest condensate running down the coil at lower temps. 72-70 on down with a low fan speed. Am planning on taking the cover off and checking into this. Possibilities are as AC Key says that the center of the coils freeze up — could be caused because the thermister or coil thermostat is mounted on the outer surface of the coils instead of the center or inside surface of the coils. Whatever the problem I agree it stems from a poor physical design of the indoor unit.

  38. Sonnycrockett Says:

    I’m a refrigeration mechanic with way too much experience dealing with these nuisance calls from a ductless system. More than 9 times out of ten, I find the water leaking issue to be an issue with the install, whether its the wrong fittings were used to connect drain, to a line wasn’t insulated properly and is now sweating, even to adding a p-trap on the drain that causes vapor lock, I wouldn’t be so quick to blame the unit. Properly installed, they work great

  39. Wally Schauer Says:

    I totally agree with Sonnycrocket who says when properly installed they work great. I really like the operation of my LG unit and my unit was installed by me and so I know it was done properly. But yet it still had condensate drip from the bottom front of the unit. I have watched it run with the filters removed and the face of the unit open. I have figured out what is happening and how to solve the problem. It is in the design of the coil layout and has to do with water flow and surface tension of water.
    I will bet every unit with this front “leak” problem is built with the same layout, and shape of “coils” and that even service techs could even figure it out if they took the time. (I know time is money) Logic would find it hard to believe from so many complaints (all over the internet) that not every “front leak” is a plugged drain. Soooo…
    I can tell you what is happening, why, where and the logic of the random pattern of “leaks” from one or two months when first installed or up to a year later.
    Anyone who is interested in fixing the problem can contact me directly. Or for $2000 I will send you the materials, tools and instructions. :)
    (Service techs whom are smarter than everyone else need not apply) :)

  40. Wally Schauer Says:

    Well, here’s my final comments about this “drippy” situation. I did figure out what was happening and finally got in touch with an LG factory rep. When asked about this his comment was “yeh, we’ve heard something about it”. Anyway it is caused by the surface tension of water. The droplets of water or condensate (essentially distilled water, which has the highest coefficient of surface tension - remember your science class when you floated a needle on water, and sunk it by adding a drop of soap to the water) are running out from an upper “coil” and staying on top of the fins of the next one in the form of a water drop (instead of running through to the next lower one and so on down to the drain pan, instead it essentially continues on top of the fins ending up in the plastic frameworks and filter and dripping down out the bottom front. This action can be easily observed by setting the temp at it lowest point, running the unit for five minuets and then shutting it off and opening the cover and removing the filters and watching the droplets of condensate run down. You will see exactly what is described above.
    How to fix this?? I initially brushed on a little Rain-X to the top of the cooling fins and it works great because it breaks the surface tension on the water droplet and it runs down to the drain pan —problem is- it washed away after a day or two. (Maybe some chemist reading this can tell us what compound could be applied permanently.)
    At any rate the LG rep says they recommend applying a foam tape to the EDGE of the upper most coil (this would be the same tape as you see just below the the “Plasma filters”), he says you can get it at your local refrigeration service dealer.
    I have done this with a silicone based tape and it has solved the dreaded “Front Drip”. You can e-mail me if you have question at Bye-

  41. Beth McLaurine Says:

    I had new LG mini-splits installed May 2011. Last month one indoor unit started heavy dripping (I have 4 units).
    I will try tilting the unit toward the drain and making sure the hose is clear.

  42. Dianne Says:

    We had a Mits split system installed in 2010, started dripping in last Dec.
    Tech out in July as started getting worse and brown spots on wall, floor, furniture. He sprayed the drain which was working fine and said it’s probably condensation and left. Tech out again last week, started with the spraying again and then said might be the refrigerant low or leaking, he left again. After 110.00 the 1st time, no charge the 2nd time but nothing fixed. I called and talked to service manager and the owner. They say they have heard of brown drips, don’t believe them. Now someone next week will come out to look at the refrigerant and another 300.00+ dollars. Can you say money pit………..the system is not even paid for yet. We got this to lower our heating bills and stay cool, we live WA state and yes it gets hot here. I haven’t contacted Mitsubishi yet. Warranty still good for about 1 year on inside, 2 years on outside.

    Does 300.00 sound reasonable? I don’t know.

    Thank you for any help.

  43. Chad Says:

    There are two things that can cause water to come from an indoor unit,1 condensate drains, mini splits come with a flexible drain line about 14 inches long therefore if it is not attached possitivly to a drain system water will drip from there,because it is flexible and there is not a very large Chanel to house the drain ,line set,and control wire between the wall and the unit its possible the drain has been trapped or rum uphill in which case it will leak from the pan the pans on the units I have installed are slightly sloped with the highest point in the center and slope to both sides there is a nipple on each end of the drain pan one with the drain hose and one with a rubber plug in it allowing you to chose the side for the the drain to terminate.2 the refer lines will condensate in both heating and cooling and are both housed in a single insulated jacket behind the unit, this jacket is split on its length for a while to make the flair connections easier. The unit should have come wit a wrap like an ace bandage to wrap the insulation tight arount the flare connections(any copper showing will sweat and drip water) and lastly if there is any oily substance anywhere it is due to a refrigerant leak probably from improper flaring of the lines call a tech imediatly to fix the leak and recharge the system, unforchanatly there is no way to know how much leaked out and with inverter driven compressors you can t just hook up gauges and cheak the prsssure you should have them evacuate all the refrigerant and weigh in a new charge

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  45. Chris Says:

    New Mitsubishi 24K BTU 2 zone. All very well installed by a reputable HVAC company. Okay so I was talked down to two indoor units and we are in heaven temps right around 68 indoor leaving the unit on 24-7. The second week of use water started appearing at the base of the main unit. So I called and let them know and they said “normal” I ain’t buying it. A product so well designed and they let water just find it’s way out of the unit? He’s coming over for a final inspection in a few minutes and I’ll let you know about the outcome. As far as professional I felt they did a good job, used a torque wrench on all fittings! SO is water coming out of the bottom of the main outside unit normal or not?

  46. Stephen Says:

    Let’s return to the first question about condensate water leaking from the indoor unit. Under no circumstances should a unit leak, not drain, or whatever. Regardless of the humidity level, and under high humidity, a two ton unit for example, will give a steady dribble of water from the condensate. This is good. The drier the air, the cooler it feels, obviously. There is no reason to “tilt” the indoor unit toward the drain side. Recently, I installed a Fujitsu and water began to blow out the front vent after some operation. What was wrong was the drain line was too high prior to exiting away from the unit, thereby filling the collection pan and then water wicking up with fan and out the front. It was a careless install and a little bit of an oversight. Once problem identified, I simply repositioned the drain tube lower. As is typical with a mini split indoor unit, there is an electrical line (4-5 wires), two refrigerant lines (suction and pressure), and the drain tube. Take this advice–install drain tube as close to the bottom of the indoor unit and not on top of, or higher than the refrigerant lines and electrical. As far as the unit being under/over charge with refrigerant has nothing to do with a unit leaking condensate water. The so-called “freezing” the coil, though can happen, and can leak water, is not a very good indicator of a condensate problem. Because at that point, if freezing is occurring, there won’t be any cooling going on. That would be among a few things, an indication low refrigerant or lack of air flow (i.e. extremely dirty air filer). I would agree the flare fittings can be problematic and leak. I see quite a few cases of this out and about. However, if properly made, and tightened, this fittings will not leak.

  47. chistie Says:

    I have had my ambiance eco green mini split for 3 years now. Never had any trouble until this year. It started leaking from the front and there is even water droplets in the display screen. I need help. I have tried everything from putting a vacuum on the end of the drain hose and blowing into the drainhose from the outside. This has helped but only for a few week. Any suggestions? anything would be great. I know the position of the drain is not the issue, since this is the first time it has ever happened. PLEASE help a frustrated farmer who likes the cool air in the heat of the summer.

  48. Jim Says:

    I too have three Mitsubishi Hyper Heat Units. The other night, the 18000 unit started blowing water out the front. I went outside and saw very little water dripping out of the drain hose. On the inside, it was full of water. I took a shop vac outside and put suction on the drain hose and right away a stream of water came out telling me it was clogged in the drain pan in the inside unit. I think it has to do with dust so the key here is to clean your filters much more often as dust will collect on the fins and as water condenses on the coils, the dust gets collected and clogs the outlet hole of the drain. It is very humid right now and there is almost a constant stream coming out of the hose now. I think as a precaution, every couple of months I will put the vac on the drain line outside and clean it out.

  49. 401G Says:

    Mine was leaking inside also. It was a clogged drain line. All you have to do is blow into the drain hose from outside, then a few seconds later water should start pouring out of the drain hose. Be sure to have somebody inside holding towels around the unit, as you’re about to make water splash everywhere and it run down the wall. You could suck on the hose to prevent this, but who knows what will end up in your mouth. YUCK!

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  51. Emmanuel V. Angod, Says:

    In fairness to the owners of split type mitshubishi electric, your company should assist customers having this problem. Either faulty design of the aircon unit, or no sufficient slope of drain line, or too far from the main unit of the system. Drainage design and installation may be faulty. What if you lost your loyal users because of this simple problem. O common, help your customers and upgrade your system.

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    I have whirlpool chrome model 1ton split AC. recently I uninstall the ac for shifting purpous
    but, after detachning the indoor unit from outdoor unit , about 250ml unit
    oil leaks from condencing pipe of indoor uint. what is the reason?
    what will be the effect of it. how it can be repaired? please help me.

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  54. Brian Hughes Says:

    Leaking of water from Air Conditioning unit makes the rust on the lower ends of the unit.If AC drain line in clogged and can’t take the water out properly, it’ll make the drain pan rusty.AC must be installed on a angle to make sure that the water gets out properly and does not do any damage to the unit.Duct cleaning of the unit makes the unit works properly and allows the water outlet to take the water out of the unit.Vacuum suction of the drain hose will also helps to take out all the deposit accumulated in the hose.

  55. brant Says:

    my Mitsubishi indoor unit is leaking water from the vanes. This unit was installed last fall so this problem only occurred recently when we first used the unit in AC mode. It appears the air flowing over the vanes as full of water which is condensing on the vanes and dripping on the floor.
    Any suggestions?

  56. dooooooolaney Says:

    I came to this site because I am a mechanic and today I had to deal with a Mitsubishi ductless split that is dripping water from the indoor unit after three years of no problems. it was easy to wet vac out the drain line from the outside but it continued to drip. I can’t see any good way to clean out the drip pan. Mitsubishi should be ashamed that there are so many problems of this kind on their expensive systems. I will post what I find tomorrow.

  57. Anne Bell Says:

    I have a Mitsubishi Mr Slim 30k btu system and I’ve had it 2 years. First year it worked awesome but second year was steadily declining in its ability to cool. I did see strange brown spots on the inside blower which looked oily. I mentioned it to the service tech when he was cleaning it and he said it was nothing. I told him something was wrong with that unit because even though it wasn’t throwing off any error codes it was not cooling. They said they will check the refrigerant to see if it’s low but they say it couldn’t be leaking. You know what I think? These Mitsubishis are junk and there is a problem with these units. I think the HVAC company that sold it to me doesn’t want to mention that they are faulty. They just want to make their money. With a unit that is needy then heck they can rake it in. I was trying to point out to them that why would a perfectly functioning AC work for the first year then by year two not work as good. I told them omething is not right. It’s just common sense. Still no answer so I’m stuck with a unit I paid $3800 for that doesn’t cool. I’m never buying a Mitsubishi mini ever again. I can buy a cheaper unit if I’m going to run into these problems and have to replace it every 2 years anyway. Screw it

  58. Darryl Says:

    My water leak on the daikin split system is do to the drain tube, the installer used the wrong Diamater Cooper tube ( to small) and the length is to long to connect the drain tube to the unit. This cause a kink in the hose and over tighten the clamp which put a hole in the drain tube that fits over the tube that tightens over tube that copper tube is in. So what is happening the water dose not flow down the copper tube first due to the fact that the diamater is smaller than the hose it flows to where the clamp is first and leaks out where the kink is and hole in the tube from the clamp. The water needs to back up enough to enter the copper tube to let it drain out the tube as intended.

  59. Emile Says:

    I finally fixed the long-standing problem of my Mitsubishi Mr. Slim leaking condensate water on humid days. The line from our dining room unit penetrated to a space above a drop ceiling in a sunken addition. I had routinely been putting a wet-dry vac on the condensate outlet to pull out water, mold, etc. that had been building up and causing the unit to leak, and I finally dug into the ceiling to find out what was going on.

    The 10-inch section of clear tubing that was connected to the unit’s drain line was actually bending down and then up again, forming a trap, and the connection to the PVC elbow that led it down to the crawlspace penetration was at the same level as the unit drain. I had to reconfigure that setup so the clear tubing ran slightly downhill. Customer 1, installer 0.

  60. amy Says:

    how did anyone get mitsubishi to take responsibility and either replace the unit, or repair it at their expense?
    they have been singularly unresponsive, almost rude, with me, mostly when i suggest the machine may have flaws

  61. Frank Says:

    I have installed an 18k Gree unit in my house with no issues. I then had an authorized A/C installer install 3 multi zoned units, and have had so many issues with this installation, from units freezing up to units not working to having the installer replace the gyprock in the ceilingthat fell down because of indoor water leakage. I have since had 3 other contractors try to repair the different issues, until I found one with experience with these units. These are great units, far superior to central units. The problems that we all have had is with poor installation of the system by contractors inexperienced with these issues. Oh they will claim they are experts, until the first problem arises, then they throw there hands in the air, and say well I dont know what the problem is, must be the manufacturer.Dont be fooled by these people, if it comes with a warrantee, make final payment after 30 days,the good contractors will accept this, the bad ones will run.

  62. SelfService Gal Says:

    My Quietside Mini Split seems to work fine, but there is nothing dripping out of the outside drainline. No leaking inside, (yet) but I’m getting worried. I am not able to see an indoor drainpan; I feel sure it has one.
    Any ideas???

  63. Andy Says:


    We have had a AC unit installed in our town house for almost 2 years now. Shortly after we had the unit installed, I noticed some small water droplets forming in the elbow that is directly next to the downstairs unit and runs up into the crawlspace between our second floor. Inside the elbow is a small box that has a float switch wired up to a pump in the crawlspace. When the tank gets full it pumps the water up and through a piece of tygon tubing that runs across the ceiling and into the drain pipe.The water that was dripping was condensate buildup on the tank and the tube up to the pump. Well, we came home today and noticed that there was water dripping out of the ceiling where the tube runs across. After further inspection, I noticed that the entire length of the tube is covered in condensate and the buildup is what is leaking through the ceiling. I ran some bleach through the system to try and unblock an algae that might have been built up, but the flow doesn’t seem to be the problem. Is there anything I can do to insulate the hose or something to prevent the condensate from even forming?


  64. John P Miles Says:

    I awoke this AM to water dripping from the unit, opened the front panel and placed my hand inside and was able to feel water so assumes the drain line was clogged. Got a small shop vac and was able to clear the line from outside. The question is is there an easy way to place some hydrogen peroxide down the drain in order to try and stop it from clogging? We do that periodically with our other AC drain lines and have never had a blockage.

  65. tassiehammer Says:

    Our Fujitsu floor mounted unit started making a hissing sound this morning and on removal of the front cover we found what seems to be an oily substance running down a copper pipe, {lagged]. Last night was the first time this year that the air conditioner was on all night. Can it be fixed or time for a new one? Its about 10 years old.

  66. Ed Says:

    We love our unit but it has started dripping water with the heat running.

  67. Ortona Cooler Says:

    Are P-traps usually installed in the condensate drain line for mini-split systems? My Diakin ductless mini-split has one in the line at its terminal end outside the attic where the air handler is located. The installation manual for the the unit (FDXA09LVJU) heat pump air handler doesn’t mention adding a p-trap anywhere—either next to the air handler or as in my case at the end of the drain line which is at least 8 feet below the elevation of the air handler. Do these units have an internal p-trap that makes adding one outside unnecessary?

  68. William Soma Says:

    I’m having a some what different problem I’m having rust particles flying out of a/c
    inspected in vents, there’s rust on these wire that guide the fans for the air to oscillate

  69. Mark Says:

    Ramsond 24000 btu min split, popping a fuse and noticed its nothing draining, its worked fine for a year

  70. Kerry Says:

    I have a 4-yr-old LG dual zone sys. The 126k BTU air-handler/blower just began dripping condensate (a tiny rivulet) down the wall. The outside drain is dripping steadily as always. Any tip on how to fix this? Thank you.

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  72. Bad Design Hater Says:

    Exactly HOW do you access a mini-plit interior drainpan to clean it? My Fujistu ASU24CL1 indoor unit seems sealed. The unit creates a lot of slime which I clean from the draining hose and a few inches inside the unit through the hose connector, but the bottom inside the unit must be full of it since the hose connector is higher than the bottom of unit (bad design if you ask me).

  73. Steph Says:

    How do you remove the blue stain once it’s on your walls? The contractor wants to solve by painting white on top - there must be a different way!

  74. Kim Says:

    I got rid of my split units and went back to Windows units, problem solved. I couldn’t cope with the drips. Too many people I know have the same issue with these split units and they all were installed by different people. Bottom line these units need to be redesigned!

  75. AC Tech Says:

    I wanted to help some people here. I didn’t have time to read each comment so forgive me if the answer is already posted. Cheap mini split ductless units such as Ramsond have a flaw causing the water to leak out on the floor. Their coils are coated with something that causes the condensing water to stick or attract to the coil, long enough for it to stay on the coil until it reaches the bottom where it can fall off into the drain pan. When that coating washes off over time, it no longer works the way intended and due to poor plumbing and engineering, you get the leak. You might be able to have someone re-coat the coil but my opinion is to buy good products not cheap ones.

  76. Dave W Says:

    I have a mr. Slim 9000 btu mini split AC that was installed 4yrs ago. Last week I noticed mold on the barrel fan and all up in the inside were the fan is . So I cleaned everything with a coil jet .Afterwards everything was working fine while in the cooling mode,no problem with condensation or drainage .Then I noticed the smell coming back,but only when the outside unit shuts down and the inside coils stop getting cold, then I noticed condensation developing on the fan,the inside were the fan is and the vanes for airflow direction.It seemed like the barrel fan was drawing out the moisture from the warming coils, spreading it out to condensate on the cold plastic airflow parts, the moisture disapates off the fan and airflow parts when the outside kicks in and the coils get cold again. This cycle keep repeating allowing for mold and that foul smell.

  77. Dave W Says:

    I have a mr. Slim 9000 btu mini split AC that was installed 4yrs ago. Last week I noticed mold on the barrel fan and all up in the inside were the fan is . So I cleaned everything with a coil jet .Afterwards everything was working fine while in the cooling mode,no problem with condensation or drainage .Then I noticed the smell coming back,but only when the outside unit shuts down and the inside coils stop getting cold, then I noticed condensation developing on the fan,the inside were the fan is and the vanes for airflow direction.It seemed like the barrel fan was drawing out the moisture from the warming coils, spreading it out to condensate on the cold plastic airflow parts, the moisture disapates off the fan and airflow parts when the outside kicks in and the coils get cold again. This cycle keeps on repeating,allowing for mold and that foul smell.

  78. Craig Says:

    I have a Freidrich Split. No drain pan - when I drop below 68 I start getting a rainstorm over the bed. I went out side and vacuumed the drain pipe, but still have the issue. I’ll take the cover off but I’d like to know how much I need to take apart and where the drain tube is located. Anyone can help it would be greatly appreciated.

  79. Anonymous Says:

    Just reading this blog. Started my sons unit today for the first time inAC mode. Water dripping off of plastic Lou Drs and running down the wall. Will check and report back. Unable to do so today as we were installing floor tile and could not walk on new tile yet.

  80. Lisa Says:

    My Lenox unit leaks on extremely humid days. A technician came out and fixed the problem. He told me this is to be expected on these really humid days. He told me to go outside & blow into the drain hose. It works.

  81. John Ratchford Says:

    I had my mini split for going on six years, I live in the Pacific Northwest, and you probably know, we generally have cool summers, but last year we had some hot humid spells, as with this year.
    Last year the air handler water drain seemed to go to small drips, and eventually, water came out of the indoor unit, I could smell a moldy smell coming from the drain tube, so I purchased a long bottle brush, small diameter, I pushed that up into the now shortened drain tube.

    The brush came back with black mold on it! So, I covered the inside unit with a large clear plastic bag, and then blew through the drain tube!out came large dirty mass of MOLD, the enviroment is perfect for MOLD growth!

    It has started again this week!!

  82. Robert Says:

    My Soleus Air Mini split is dripping water from the indoor unit. Does anyone have a service manual for the unit? Can it be taken apart without having to evacuate the lines? I just want to remove the face frame to look inside. Soleus offers NOTHING on these products but installation manuals. Help. Thanks.

  83. Faizia kamran Says:

    I have installed two mr slim two years ago and both have same problem gas leakage from indoor unit.

  84. Trudy Wohlstrom Says:

    I have had my Daikin mini splits for about 6 months. I have 5 units and I can honestly say I hate them. We cannot run them unless I want water pouring out everywhere. I have had the installers here several times but they have no clue what to do. Sure wish I had my money back. They are Junk! Never buy ductless air units.

  85. Richard Says:

    Should power to unit be shut off or is turning unit off fine before investigating an inside water leak?

  86. King K Says:

    I have a LG LSN307HV3 and it was installed by a LG Excellence Contractor back in May 2016. Two months after installation, water started to drip from the indoor unit. Installer says that the plastic cover is touching the coil. Water was dripping from the top coil and didnt drip to the lower coil, but was draining properly to outside. Installer had to come back several times but kept putting foam tape onto the bottom end of the upper coil. After several attempts, the installer installed a metal bar/brace/guide across the indoor coil by removing the front cover. Was informed that its an LG part. What a nightmare it was to fix it.

  87. Anne Gee Says:

    I was considering installing ductless to replace a traditional ducted system that has died of old age. This is a tiny urban space and the ducts are unsightly ( they hang down from the ceiling), also the idea of freeing up a closet is appealing. But these comments are making me think twice! Have these units gotten any better in the last few years? Are their any statistics on how many installs have these kinds of problems and how long on average they cost?

    Cost for install is already much higher than I expected and the thought of it lasting only a couple of years is sobering.

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