It's terminally ill. Buy a new one.

It's an air conditioner, shouldn't it be set to a lower setting to operate? the colder the thermostat is set the more it will cool the surroundings. maybe it is set too high to activate.

It's filled with freon, a gas that cools the air, and your unit needs to be refilled every ow and then....;same as in the car, needs to be refilled every year.....

It need's freon.

Sounds like it's out of whatever coolant it needs.

while it is running do you hear the sound of it change from a sound of no humming to a low pitched hum, if not then the compressor may be bad, try putting it on a low/cool setting and then listen for the low pitch hum and if it sounds like it is coming on , and if the back of the a/c is extremely hot then it is a sure sign the compressor is bad, but if the compressor seems to working then I would suggest turn off the unit and unplug it then if you can take a garden hose or a cool bucket of water and spray or pour the water over the back side that is hanging out of the window and then let it cool off for a bit and then turn it on also make sure you unit is leaning back so that the water that condescends can drip off the unit , if none if this works it may just need some freon, if you can remove the back cover off your unit and check the hose that goes into the compressor and if it feels cold then the freon is not flowing properly , hope this helps , we had this problem over the summer with our central unit and I learned alot from the a/c repair person that came out, but ours was the fan went out in the big unit that sends all the air through the vents which a window unit doesnt have the big fan but you may want to check the fan and make sure its running properly as well ,, good luck!!