Troubleshooting Portable Air Conditioner

[Which Roger]

I have a 2-year-old LG portable A/C (the kind that sits on the floor and blows the warm air out a window vent via a big hose). Yesterday, I plugged it in for the first time this season, and it's not cooling at all; just blowing air around at room temp. All controls and displays are normal (it displays the current temp correctly and allows me to set the cooling temp). I think that the problem is that the compressor is not running; I don't hear the low-pitched hum normally associated with a running compressor. I believe there's an internal breaker that trips if the compressor becomes overloaded, and I think this is the most likely cause, but I thought that it is supposed to reset itself when the condition clears, and that's not happening. Is there anyone out there who understands this mechanism and can explain it?

Of course, it could be something worse (compressor gone bad, lost coolant, etc), but I'm hoping my theory is correct and that I can figure out how to un-trip the compressor breaker.

(This is the one problem I've had where there's absolutely no discussion on the internet, and the product doc is pretty worthless.)

 

[hankster]

I think you're on the right track regarding the compressor. There may be some type of thermal overload for the compressor inside the case. Not sure if it should reset automatically or if there is a manual reset.

 

[Which Roger]

I think you're on the right track regarding the compressor. There may be some type of thermal overload for the compressor inside the case. Not sure if it should reset automatically or if there is a manual reset.

Thanks for the encouragement. I think I'll carefully remove the casing and see if I can find something like that.

 

[bjorn2bwild]

Two other things to check if the compressor is not running - capacitor and pressure switch (low on refrigerant).

 

[yakers]

Had a couple of these over the years and they hve a short life expectation, maybe as little as two years. Check consumer reports and online. Mine just gave decreased cool air until it wasn't worth running them. And they appear to put a heavier load on the electrical system then what their watt rating would indicate.

 

[travelover]

If you replace it, go with a two hose model. Blowing out conditioned air and having it made up by hot air leaking in from outside makes for very inefficient cooling.

 

[NW-Bound]

A bit of probing with a $5 DVM at Harbor Freight (often given away free too) will pinpoint the cause of loss of power to the compressor. The things to check include any circuit breaker, thermal fuse, coolant pressure switch, etc... Or perhaps the thermostat fails, and says that the air is cool enough and turns off the compressor. One can just check for power at the compressor terminals.

If the compressor gets power and does not run, it has burned up internally, and one can check for that too.

By the way, as travelover has noted, a 2-hose setup is highly recommended. Else, the exhaust air will be replaced by outside hot air sucked in through door and window leaks all around the house, making other rooms hotter.

 

[Which Roger]

New data point: I believe the compressor is running. I removed the back, can feel the compressor vibrating, and the surface gets hottish as the unit runs. Also with the back off I can hear the compressor running over the noise of the fan. But, not a bit of cooling.

LG web site has automated help where you check boxes based on symptoms, but its conclusion, for no cooling with or without compressor running, is that the unit will need to be serviced. No way I'll pay for that, since it wasn't that expensive to begin with and is a couple years old.

I'm not real confident I'll be able to do anything, but I can't make things worse.

BTW, we have working central air in the house, but got the portable unit for the kind of weather we're having of late, where the downstairs (where the thermostat is located) stays cool enough that the central air doesn't kick in, but the upstairs bedroom gets warm enough to be uncomfortable and needs some cooling.

 

[NW-Bound]

Maybe there's been a loss of coolant. Home HVAC's or car AC's all have a pressure switch to turn off the compressor for loss of refrigerant, but perhaps small portable ACs do not have it.

Home and car ACs also have a refrigerant inlet port where one can check for pressure and to recharge if necessary. Refrigerators are generally completely sealed systems where the port is pinched off and brazed shut at the factory. There's no place for a refrigerator to leak anyway, short of a pin hole somewhere in the tubing. I do not know the customary set up for a portable AC.

 

[Bamaman]

The portable units don't seem to be very durable, and I have avoided them in the past. They're also not that inexpensive, either. You can still buy window units for very low prices, however.

The mini-split systems are going to be the a/c systems of the future--used throughout the world more than in the U.S. I'm seeing more and more of them, however.

 

[Sarah in SC]

I'm a giant fan of the mini splits, though we have a regular unit in our home. I did a lot of research on them for our little efficiency that we plan to build, and will definitely go that way when the time comes.

Window units work, but are unsightly and take up a lot of room when in use. But cheap and easy.

 

[NW-Bound]

Yes, the mini-splits can have very high SEER. Some use new-technology compressors, which can run at variable speeds, not unlike the motors in the EVs, and do not have a high surge current when they start up like traditional AC induction motors. Installation is also easy, and they have made them so it's no problem for DIY'ers.

The main problem I see with them is that there's no easy way to share one unit across multiple rooms, although I have seen some with multiple evaporators (multi-zone).

 

[Walt34]

New data point: I believe the compressor is running. I removed the back, can feel the compressor vibrating, and the surface gets hottish as the unit runs. Also with the back off I can hear the compressor running over the noise of the fan. But, not a bit of cooling.

LG web site has automated help where you check boxes based on symptoms, but its conclusion, for no cooling with or without compressor running, is that the unit will need to be serviced. No way I'll pay for that, since it wasn't that expensive to begin with and is a couple years old.

Normally on A/C equipment the sealed system warranty is five years but I'm not familiar with the portable units. It may be worth the time to look up the warranty if you still have the owner's manual and receipt. Or the serial number or data plate may indicate the year, if not the exact date of manufacture. If those are within five years it would still be covered under a five-year warranty even if you don't have the purchase receipt.

We keep a folder with appliance manuals and when I buy one I staple the receipt to the first page of the manual. A couple of times that practice has paid off.

 

[Senator]

If the compressor is actually running, it will get hot. Seldom does the Freon leak out, but it is possible.

Often, if the compressor runs, it is a matter of cleaning the cooling coils to make it run better.

 

[Mulligan]

I'm a giant fan of the mini splits, though we have a regular unit in our home. I did a lot of research on them for our little efficiency that we plan to build, and will definitely go that way when the time comes.

Window units work, but are unsightly and take up a lot of room when in use. But cheap and easy.

I just installed my window unit for the summer. Paid for itself the first year I bought it, now on year 3. I love a very cold bedroom to sleep in at night. Do not love AC bills cooling an entire house to 66 nightly just to cool my bedroom.
Btw- Window unit unsightly? It looks flat out hideous from outside. But since only the back yard trees notice it, no problem. Personally I wouldn't have put it in if I had a front facing bedroom window.


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[38Chevy454]

If the compressor is running, and the fans (two: one for the condenser which makes the hot air that goes outside, one for the evaporator which makes the cold air blown inside) are working, then you either leaked the coolant or need to clean the coils. Since the condenser and evap coils are both heat transfer devices, cleaner is better. If cleaned up and still not working, then about the only thing left is coolant leaked out. Most of the small units do not have a fill or pressure port, they are factory filled and considered a sealed system that is not supposed to leak or need service.