LG LW1810HW air conditioner... The unit is cooling, blowing, etc just fine, but had been off for a few weeks... When we turned it on again, it immediately started vibrating, shaking the whole wall. Any idea what we need to check out?

Supply fan motor is either shot or needs to be cleaned. Generally if the whole wall is shaking there is a bearing out on the motor.

I’m happy to assist further over the phone at https://www.6ya.com/expert/robert_54ae41aaaffbab00

I just experienced this problem myself. What helped me was cleaning out the lint trap. My guess is that the until sucks in air through there, then conditions it. Blows the cold air out the top, and hot air out the tube. When it can't suck a decent amount of air in, the condenser can only condense so much of that limited amount of air. When it runs out, the unit just runs the fan until enough air has been condensed.

My lint trap was filthy, hadnt Bern cleaned in years. Soon as I popped it off, the unit started belching out cold air nonstop. Clean your lint traps! Don't make my mistake!

It has lost its refrigerant charge again. Have someone find and fix the leak before recharging or it will just leak down again.
Hope this helps

Unit may be freezing up if blowing ice crystals. Let thaw 24hrs try again. Make sure condensation drain line is cleaned out.

Hi,
The unit is probably low on freon and so it is running too cold....this trips the freeze stat and shuts down the compressor till it warms up and you reset it by turning it off and then on again...
The unit will need to be recharge or replaced...

Here isa tip that I wrote about how to add refrigerant to a air conditioner or coolingsystem

How to add Freon to a Air Conditioner or Refrigeration System

heatman101

your compressor motor is no good Time to replace unit

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Hi,
Your unit is freezing up...check the air filter...
Here is a tip about troubleshooting your air conditioner...
There are many things that can cause your air conditioner not to cool…

Air Conditioner Trouble - Review the Possibilities

heatman101

It sounds like the compressor is not coming on in the outside unit. If it worked fine and was cooling before, then your compressor probably over-heated and tripped the internal overload switch which causes it to stay off while everything else is working. The most common cause of your compressor over heating is an incorrect refrigerant charge, though it could be a few other things like a restriction in the copper line set. You will be able to hear the fan motor and the compressor kick on if you listen close while the system first turns on. If the compressor is over-heated, then after it cools to a save temperature, it will come on again, but only till it over-heats again. I would have the charge checked on the system, but remember that if the compressor is over-heated when the technician gets there, there is nothing he can do until it cools down and time is money! It's best to not run it until the problem gets figured out. Hope this helps and points you in the right direction. Good luck!

www.appliancefactoryparts.com/content/.../118816.pdf - United States
Above is your service and repair manual, with this you will be able to troubleshoot and repair your Aircon.
I suspect, your thermostat may have a faulty sensor?
factoidz.com/troubleshooting-your-air-conditioning-thermostat/

http://www.inspectapedia.com/heat/Thermostats.htm

Below is a DIY AC, troubleshooting how to. http://www.repairclinic.com/Air-Conditioner-Troubleshooting

our unit is realy a coleman unit but You did not have that listed.
In any case it started back up again and I was so releaved as it was at least 103 degrees yeasterday. But i haove a feeling this may not be the end of it .
I may need your service at a later date.
Thank you for your quick response.