Air Conditioning - Window AC unit question

I have a Panasonic 12,000 BTU window unit, the model number is CW-XC123HU, it's roughly 3 years old. It's not blowing cold air at all. Just the warm air from outside, so I guess the fan is working. I checked the filter and it's clean. It's been running just about 24/7 for two years as I live in Honolulu HI. I did turn it off then back on again and that didn't work, still just the fan blowing hot air. Does it sound like I need freon? Would an AC unit that young need that already? Is freon something that is cost friendly or should I just go buy a new unit? Sorry Im so clueless! Thanks.....

12.000 isn't all that high and if you have been running it constant for 2 years no wonder it's done. You could enquire as to how much it would be to charge it but might end up not being much less then to get another

Those units are very quiet and you may not know if the compressor is running.

Occasionally the thermostat goes out of range and if yours is a bulb type you could try something.
Remove the cover and look to see if there is a bulb about the thickness of a pencil in front of the inside coil.
If so then take a dishrag and soak in hot water and wring it out.
Before it gets cold wrap it around the bulb and see if it starts.

That's about all you can do.
Compare the cost of a replacement to the cost of a service call.