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Condensation on exterior bottom of window A/C unit

Hello! I hope to get some thoughts on an issue I have noticed with a new LG 10,000 btu window air conditioner installed this week to help deal with the humid summers of St. Louis. I'm familiar with the need to install the A/C so it slopes down towards the outside of the building, so I use wood pieces to raise the height of the window sill so the unit will clear the storm window frame. The drain hole of the unit is clear, and there are no obstructions within many feet of the unit.

The problem I am having is condensation is forming on the outside of the unit, primarily on the bottom on the side where the drain hole is, but also a bit about halfway up the side wall of the unit, again on the same side as the drain hole at the back rear of the unit. The condensation droplets on the bottom can be seen from where the side curtains connect near the front of the A/C unit all the way towards the back corner of the unit outside the building. I'm concerned because some of this condensation is dropping onto the wood I use to raise up the sill on the inside of the window frame, and also that water will end up collecting on the outer sill between the window and the storm window frame, eventually soaking through the sill into the walls if it can't weep out quickly.

I've never seen this much condensation on the outside of my other window A/C units before. When I installed the unit I noticed that the tips of 3 screws were poking through the bottom of the unit case at roughly the center of the bottom of the case, could this be contributing to the problem? Or is this just normal condensation because the outside temps are around 90 with a heat index of over 100 when the high humidity is figured in?

I've already reworked the slope of the unit twice in case that was the problem. Currently the unit is sloped so the back is approx. 1/2" lower than the top of the unit where the window guard is, per the manufacturer's instructions.

I appreciate any advice or suggestions that you have to offer. Thank you!

Re: Condensation on exterior bottom of window A/C unit

I'm stumped---you say the drain hole is open & clear---so the only suggestion I have is to check to see that there is a free flow of water coming from the drain hole---just a small piece of crud is enough to block these drain holes, such as mold, etc.

By the way you describe it, it sounds like there is a blockage or partial blockage of the drain water & it is building up inside the lower portion of the unit.

Many new units are shipped with a PLASTIC PLUG in the drain hole that has to be removed before the AC is put into operation---run a piece of hanger wire or similar into the hole to make sure there is no obstructions.

Re: Condensation on exterior bottom of window A/C unit

I'm glad I'm not the only one who is stumped! The unit has literally been out of the box for only 3 days so I wouldn't expect an obstruction from mineral build-up, etc. I did pull the rubber stopper out & inserted the drain 'extension' piece when I was getting the unit ready to install. The instruction book didn't say anything about the drain hole or removing the plug, which I thought was odd. The unit is draining very well though. I wanted to make sure of this so I checked on it periodically while running, the drips from it were very regular, similar to my other A/C units. I can't actually use a stick, etc. to push through the hole because the entire backside of the unit is the metal 'grill' or 'mesh', I'm not sure what you would call the type of material, but it extends behind the drain hole in the exterior metal case as well. Thanks for the reply!

Re: Condensation on exterior bottom of window A/C unit

I would try to contact them at the numbers listed below---they should give you immediate & free support on this new product---remember, if it's going on in one of them, it's going on in many of them, since they're all made on an assembly line & are exactly the same.

Try to speak directly with the repair technician, and not an operator/receptionist, etc.--there's little doubt their techs are well aware of this problem & can give you a quick way to fix it.

The LG website lists a LG factory service technician at 800-243-0000.

They list 2 authorized service centers in the St. Louis area: Mid American Electronics in St.Charles at 636-928-4131 and AAA Appliance Heating & Cooling in St.Peters at 636-928-4933.

LG lists another 800 number in San Diego: 858-635-5300.


Re: Condensation on exterior bottom of window A/C unit

Not an HVAC guy here but gotta say that Nashua Techs posts are great. Always well researched and packed with great info and knowledge.

Re: Condensation on exterior bottom of window A/C unit

Hi All - Just wanted to post an update on my issue for any future readers. After the new A/C unit ran for a portion of the day over the following 2-3 days, the condensation amount decreased. I did pull out my little level & found that the unit was tilted slightly towards the left side, where the condensation was mostly collecting & the drain hole is. So I re-leveled the unit from left-to-right, maintaining the existing pitch down towards the outside of the building. Within a few days the amount of condensation collecting was not a concern, even after running the unit for a full day & night I did not see the same large amount of water drops on the outside bottom of the case anymore. I have a slightly smaller LG A/C unit in another window, so I compared the drain hole configuration, etc. between the two units - both looked exactly the same so at least from an external examination there is nothing about the new unit that seemed non-standard.

I wonder if it just had to adjust to it's new home in my window. Also I've kept the temperature setting much higher than the 60 degrees that it is set to by default when you first plug in the unit. So I don't really have an answer or cause, but after monitoring the unit over 2 weeks I am comfortable that there isn't water collecting & getting into my exterior wall.

Thanks again for the help!

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