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Cleaning and fixing split system air conditioners

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Cleaning and fixing split system air conditioners

Sample unit: LG LM125HVT (LMN126HVT and LMN096HVT should be similar)

by Dr. David Zatz

Split-system air conditioners are billed as an alternative to retrofitting central air conditioning, in houses that can't accommodate a refit. They are quiet and powerful, don't require ductwork or "the giant squid" in the attic, and are still more efficient than window units. You can set the temperature for each room separately, so if you have an office that gets hot from running computers, it can get more cooling.

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There are down-sides, though, that generally don't come up during the sales phase. One of those is the fact that you do have to maintain them; another is the much higher cost of service and repair. With a traditional central air conditioner, there are two major units, compressor and evaporator, one inside and one outside; and once the system has been installed with all its ductwork, you can replace all the functional parts relatively cheaply. Chances are you won't have to; they last for decades, and parts are usually available for decades as well.

Split systems work wonderfully for a year or two, and then things may start to happen. Let's start with problem #1 - water suddenly starts flooding out of the air conditioner. Regardless of brand, these things rely on tiny little drains, smaller than the head of a small machine screw. The hoses that carry water down to the outside of the house are huge; the ones that feed them, in the unit itself, are small and easily clogged. Here's a closeup of one.

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You should be checking the air filters every few weeks and cleaning them, but the drain will still clog, and mold will build up if the water can't get out easily, so let's look at how to service them. I have the LMN-125HVT, an incredibly poorly designed example of the genre; the older split systems I see are Fujitsus and Mitsubishis, and the replacement for these LGs, when they break down next (there are no replacement parts at distributors, and ebay is sure to run out), will be one of those two.

Before you start, go to your favorite local or online retailer and get some of special blue tablets and cleaning spray. Before these arrived, I used orange drain cleaner because, well, I had it. The orange drain cleaner worked on two units but didn't do much for the third, so I waited for the blue tablets on that one. (It did help.) You will also need a flashlight and stepladder high enough to let your eyes get around midway up the unit. Oh, and shut the power to the air conditioner. These usually have a fuse outside that you can pull.

Preventing drips and mold: Cleaning the drip tray and water hose

First, take off the decorative cover. You do this by a combination of wiggling, jiggling, and bending. Get used to that method. The engineers chose a low-grade, thin plastic for these units so they could avoid actual engineering of "take it apart and put it back together" devices.

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You can take off the filter if you want to and clean it. But you don't have to, for this.


Now we have the top cover. Again, you carefully lift and bend and twist and jiggle until it comes off with a loud crack that is usually not the plastic breaking (so far this has not happened to me).


You have a choice now. If you take off the louver, you will have better access to the fan. You can also bend it down a little, at least on our LG, to get at the three screws on the bottom of the unit that hold the case on. The only way to remove the louver, based on watching two professional HVAC guys, is indeed the bend-and-twist, including pushing one of the black holders in the middle. Maybe Fujitsu or Mitsubishi has a better system, maybe not.

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Now you take off the case, a fairly simple operation involving pulling the case down, out, and up. It's hard to describe but essentially you have to clear the stuff on the bottom and then clear it on top. Watch out for the wire clip.

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By the control panel, there's a little wire clip you have to remove. I really have to applaud LG on this one, because they give you a long cord and an easy clip - there's a release you press and it comes right apart. They could have been a lot nastier and saved three inches of wire per unit.

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Now you can find the tray. Everyone talks about the tray but few show you what it is. It's the black thing that runs below the evaporator fins, all the way around the unit. The drain itself, on the LG, is right next to the electronics. If I can repeat the earlier photo?

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You can barely see it and it is a nightmare to photograph, but this is what it looks like close up. It may be filled with water and it may not...

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The test, if you want to do it, is to take a small indoor watering can and pour some water in there, and see if it drains down quickly. Each of the air conditioners I tested was clogged. I used the orange cleaner in all three, waited a couple of hours, and flushed it out with the watering can. Suddenly they went from barely moving water out at all, to being able to suck down an entire watering can's contents as quickly as I could pour it.

Putting everything back is pretty simple, but if you took off the louver, make sure you start putting it back on in the same position you took it off from, because the right side is shaped to fit a cut in the rod - the louver is moved by a little motor and if the two aren't lined up, either it won't go back together or you'll damage something.

Noise reduction: ending the clicks and snaps and cracks

There are several reasons why these units can make a lot of noise, but one of them is because they're made of a nasty flimsy plastic that's barely held together with ill-fitting snaps, and the installer probably didn't put it on right anyway.

To fix these, take the plastic bits off as shown below, and reinstall with little bits of a thin foam window insulation or felt or some such, but be careful, because anything that can get wet will grow mold; felt at the top might work but lower down you will want something that's mold/mildew resistant.

The idea here is to add just a little pressure to some contact points and to remove plastic-to-plastic contacts elsewhere.

If the unit creaks when you press it in various places, try adding the foam here and there - you don't need much! - and then see if it still creaks when it's back together. My noise issues were solved by this, which is good, because one more night of snap-crackle-pop and I'd have used a sledgehammer instead.

Replacing or cleaning the fan

You will probably need to clean the fan, especially if it stopped working, started making noises, or works slowly. The best way to do this, in my opinion, is with a spray (using a plastic bag sold at absurd cost for this purpose to hold any water or overspray) with the air conditioner still mostly in one piece but the cover off. I have not done this yet.

To clean the fan with a brush, you don't have to take the case off, but you do need to take extra steps:

  • Take out the metal "no fingers in the fan" grille, which is also a bend and twist.
  • Now you are only blocked by the left-right air directors, which I'll call "tabs," because they are essentially tabs that attach to the a/c unit and to a flimsy piece of plastic that pulls them to the left or right. It's a little difficult to pull them back, towards the wall, so they pop off the little poles and are only attached to the "rod."
  • Thread the tabs and the left/right plastic band so they hang out of the unit. Detaching them is hard and unnecessary.
  • Putting them back is tougher because as you pop them back into place, they will sometimes come off the band, so then you have to take them off again, attach them to the band, then clip them back in place. Make sure you at least put the far left and far right tabs back in or you will have problems.

You can, however, take the fan out, which is how our HVAC man did it. I copied him before realizing they made sprays for this. In fairness, the sprays are messy and smelly and really designed to be used outdoors.

No photos here, but for the LG LMN125HVT, the method is:

1) Take off the cover as shown above

2) Remove the black plastic cover held on by two screws at the far left. You will need to move the evaporator up and out a little, which is why this is a bad way to do it.

3) Go to the right side of the unit and move the fan around by hand, little by little, until you see a gap in the fan blades. That allows you access to the set screw. Use a socket wrench with an extension to remove this - don't bother with the Philips screwdriver, they really make them tight at the factory. Since the fan can slide from left to right once this screw is loose, make darned sure you know where it is right now - take a photo or mark it or comething. Now loosen the screw as much as you can without removing it entirely.

4) Back on the other side, the fan should move a little left to right and back; if it slides easily, lift up the metal coils (by one of the copper pipes) just enough to get the fan sliding out. Now you can scrub the [email protected]$*&! out of it to get the black gunk off. To put it all back, just be careful you have the fan positioned well left to right, and try spinning it by hand to make sure there's no noise or binding before you get it all back together.

You can probably figure out why I don't like this process: you have to move the evaporator, which means bending pipes back and forth, which means a chance for the unit to have a catastrophic failure.

Some reasons I think LG was not even trying

  • Teeny tiny water outlet (units sold in India have a much better one)
  • Crazy defaults for heat and cold
  • Thermostat moves in 2°F increments
  • There is a dehumidifier mode but it has no settings
  • You can only get "monsoon mode" in India (high performance dehumidifying) - not Florida, for example
  • The same thermistor broke in four of our units, and yet the company no longer sells that part, and didn't have any stock in North America when we needed it
  • There are no instructions for installers, just a not-very-helpful "pull apart" diagram and spec sheet
  • "Jet Cool" drops to 64°F after 20 minutes. Really? Does anyone want 64°F?
  • To change modes you have to slide the remote cover down, but Jet Cool is right there were it can be confused with the fan
  • Heat pump doesn't really work
  • User documentation is generally unhelpful and belabors the obvious while leaving out anything important
  • Installers don't seem to get any training
  • The left-right vent tabs are cheap and hard to remove and reinstall
  • If you mount the unit in a corner, blocking the left side access, the fan is darned near impossible to take out
  • The units are cheaply made pieces of crap

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1 Posts
My air conditioner often breaks down, I often turn to experts for repairs. My air conditioner is quite old, so every year I change some details of it. I think I will have a new air conditioner assembled in two years. When my conditioner was broken for the first time, I thought I would have to buy a new one. But users from the forum advised me to turn to these guys for help. They helped me; I call them every year to have my air conditioner diagnosed. I hope I won't have to buy a new air conditioner soon.

1 Posts
It is a very cool thing. And this is a solution to the problem for those who cannot install air conditioners of a different format at home. Of course, they sometimes need cleaning, but I don't think that's a problem. Well, if my pipes get clogged, I turn, for example, to the guys from the site
Privacy Policy - The Drain Cleaning Service, and I think the same thing is done by people who need to clean the air conditioner. It is quite normal, in my opinion. And the air conditioner is cool!
1 - 4 of 4 Posts