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
Problem:
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.
Solution:
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.
August 1st, 2010 at 10:12 am
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?
June 17th, 2011 at 9:40 am
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
July 6th, 2011 at 4:00 am
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.
August 2nd, 2011 at 6:14 pm
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.
August 17th, 2011 at 3:22 pm
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.
August 17th, 2011 at 5:11 pm
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.
August 21st, 2011 at 9:50 am
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.
August 25th, 2011 at 4:36 pm
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?
September 8th, 2011 at 1:34 pm
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.
September 22nd, 2011 at 1:09 pm
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.
October 11th, 2011 at 2:15 am
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…
November 1st, 2011 at 1:18 pm
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?
November 25th, 2011 at 12:33 am
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.
April 6th, 2012 at 7:54 am
Most of the leakage happen to do something with the drainage or the duct. Also, there are some other possibilities too.
April 19th, 2012 at 3:17 pm
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.
May 17th, 2012 at 6:09 am
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
July 15th, 2012 at 4:24 am
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.
Ajay
July 21st, 2012 at 1:35 pm
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?
July 30th, 2012 at 9:15 am
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.
July 30th, 2012 at 9:53 am
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.
August 11th, 2012 at 5:51 am
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?
August 14th, 2012 at 1:13 pm
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.
September 18th, 2012 at 8:42 am
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September 20th, 2012 at 11:07 am
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
September 22nd, 2012 at 8:40 am
Thanks so much for this.
November 3rd, 2012 at 9:07 pm
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.
stevethemechanic@yahoo.com
April 30th, 2013 at 9:11 pm
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