Air Conditioning - in-wall unit only hums when turned on

My 220V Airtemp thru-wall unit worked yesterday. When I turned it on today (low fan is first), I only heard a hum; no air blew out of the unit. If I then turned it next (low cool), I then heard a louder sound (more buzz than hum) for about 5 seconds then I again only heard the hum. This holds true for any fan setting (hum) or cool setting (short buzz, then only hum). The fans are able to be spun manually so there doesn't appear to be any seizure. I am getting a good voltage reading from the outlet so I don't believe electricity is an issue. Other than that, I am open to any ideas from all of you and I thank you in advance for any help you can provide.

You might try a capacitor on the unit that would be cheap and easy.

I am not familiar with A/C technology. I have found an image of the capacitor for my unit and believe it would be something I could replace. How do I find the capacitor on the unit? Do I have to remove the unit from the sleeve in the wall to find it? Sorry for the lack of knowledge, but I would like to try to fix this myself rather than buy a new unit if it's not really necessary. Thanks.

Would the capacitor be in or around the same spot on all A/c units? I don't know where to find it? Thanks again.

I would suggest doing a Google search for capacitors so you can see what you are looking for. Some of the wall units will use some odd shaped capacitors some will have two seperate ones some will have dual but it will be obvious once you trace the wiring from the compressor and fan motor they will have a wire that goes to the capacitor. You may have a bad compressor or bad fan motor but the capacitors are cheap and fairly easy to replace so I would give that a try before I trashed the unit. you will need to remove the unit from the wall sleeve to access the capaciotr and while you have it out be sure to clean the coils.