a/c window unit not working pproperly

Problems related to residential installations.

a/c window unit not working pproperly

Postby lulu71730 » Fri Jun 03, 2011 6:58 pm

I have a LG model # LWHD2500ER a/c window unit, it’s only 1-2 years old, recently my hubby cleaned it and now it’s not working properly. It really doesn’t matter what temp it is set on the compressor will kick on for about 4 mins and cut off then if we wait 5-8 mins and change the temp setting sometimes it will come back on after a fews minutes so if we continue to do this it will kick on every 20 mins or so(most of the time) however after the sun goes down about 8 -9pm it starts working right??? Is there a way of testing the thermistor or the control board? Or could something be stopped up because I haven’t noticed it draining or even producing condensation idk if it is draining at night???
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- a/c window unit not working pproperly

Postby 4ftBanger » Sat Jun 04, 2011 7:30 am

Window units don't have a lot going on that can go wrong. Many of them only have 1 motor that turns both the fan blades. 2 coils, and a compressor and very simple controls. The main protective control is a temperature switch in the compressor. If the compressor gets hot this switch opens, shutting the compressor motor off until it cools down. Primary causes of a hot compressor are a dirty outdoor coil or a low refrigerant charge. It's less likely, but also possible that the temperature switch is bad and opening at too low of a temperature.

Thermistors are just little temperature sensing resistors. You can measure the resistance - I'd generally expect anywhere from 20,000 to 200 ohms depending on the resistor and the temperature at the time. As long as it's not 0 or OL (infinite) it's usually considered good. As for the board - as long as everything else is working, fans, lights, display, etc I wouldn't suspect the control board until other things have been checked and eliminated. You said that at night the compressor will stay on which seems to indicate a temperature dependent issue. A normal board failure would likely show multiple symptoms and/or consistent behavior. It would be pretty rare for a board to fail and only affect one component (your compressor) intermittently.

To do a really thorough cleaning on a window unit you have to take it out of the window and take the outer metal casing off to get to the back side of the coils. Cleaning from the outside might not be enough to remove the dirt that gets embedded in the back side coil surface. Checking refrigerant charge might be more involved as these units are considered "sealed and non serviceable" the manufacturers typically don't install fittings to connect manifold gauges to. The servicer would have to install piercing valves on the lines to connect the gauges and check the refrigerant charge. It's sometimes cheaper to replace a window unit than to diagnose and repair one...
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- a/c window unit not working pproperly

Postby nomadpeo » Sat Jun 11, 2011 4:19 pm

i concur with mr. banger. over 5 yrs, not worth fixing. interesting though, that the failures started after cleaning. i suppose it's possible if the unit was taken out, that a cap tube could have got nicked or water in the controls area. but like he said, other things would be whacked out too.
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