My just over 1 year old upright freezer is no longer keeping its contents frozen, and it makes a loud continuous humming sound. I noticed that the door had been left cracked open (about an inch) for about 6 hours, which explains why certain item inside thawed. I increased the freezer temp control knob to the highest (fast freeze )setting, but colder air is not coming out.
Hi.
Try to defrost the freezer overnight with door open.Best to unplug it.
Se if that will make a difference.
Post the results.
Simon.
I was unable to unplug the freezer, so I turned it off, removed all of the contents and left the door open overnight. The compressor crackled and had a bit of a burnt smell (which I had read somewhere was normal). The next morning, I turned the freezer back on to a mid-level setting and closed the door. And, fortunately, it works again! Thank you for saving me an appliance repair call and fee:-)
I was unable to unplug the freezer, so I turned it off, cleaned out the contents, and left the door open overnight. The compressor did crackle and smelled a bit of smoke (which I had read is normal). The next morning, I turned the freezer back on and closed the door. It works! Thank you for saving me a service call and a repair fee 
Hi.
I’m glad that trick worked.
Simon.