Amana TZ21RL, MFG number P1157601WL

Had this problem years ago, let it be for a year or two, then had a week long power outage in August '20. Took the opportunity to thaw and air it out for a day, and replaced the worn fridge door seal.

It frosted up again this past December after being problem free for 16 months.

Two weeks ago, had a problem with the fridge temp getting too high and my thermometer getting a max reading of 42F. So I turned both the freezer and fridge levers up a notch. Then it got too cold and things started freezing, so I turned the settings back to what they were before and it's been fine for a few weeks. Back to staying between 33-39.

It's a 20F day, so I currently have everything in coolers outside while the fridge is left open to defrost.

One of the holes in front is clogged with ice, as well as the left rear duct.

Both fridge and freezer seals are OK. Took a cover off the back, detached the drain tube and it's clear.

Pics:
https://imgur.com/a/xEWxb3S