I'd start by making a call to LG's technical/customer support line to see what they can suggest.

Personally I would not spend a lot of effort on diagnosing and attempting to repair this. You can buy a new one for $150 (probably less now that summer is almost over as some stores won't want to store merchandise).

You're not likely to find a new 8k BTU unit for $150. Maybe $250.

Still, like most mass market appliances these days, window air conditioners aren't really meant or designed to be repaired. They're effectively disposable, kind of like diapers. :(

That's a shame, not just because of the waste, but also because a lot of trash haulers will leave it on the curb. They don't want to deal with the refrigerant, no matter what type it is.

If you're lucky, you may have a recycling center nearby that will reclaim and recycle the refrigerant If you're really lucky, you won't have to pay them to dispose of it for you.

BTW, I suggest that you check out online reviews for the brands before you buy this one's replacement.

A good guess it's low on refrigerant, and the evaporator coil is freezing up. That would mean there's a leak, and it's not worth fixing.

The owners manual contains the notice, "When the unit operates in extremely hot weather, it turns of automatically to protect the compressor." It also advises you check/clean the air filter twice per month.