Fridge ducts clogged with ice - Amana TZ21RL

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.

Both fridge and freezer seals are OK.

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.

 

Have you checked the defrost components?

 

That's only a fridge group. Not a complete model number.

There are two controls.
The main temperature control has the off position on it. This monitors the freezer temp.
The other control may say fridge - freezer or min-max. That control operates a damper that allows cold air to flow between the freezer and fridge. You don't want to change them both at the same time. Typically you put that in the middle, put the thermostat in the middle and let it run for a day. If the fridge is warm up the thermostat one number/setting and recheck. After that use the damper to balance the temp between the freezer and the fridge.

As Dane mentioned you could have a defrost problem or more likely you have a clogged evaporator drain line. The evaporator is the cold coil in the freezer. There is a heater element built into it. At certain times the compressor shuts off and the heating element cycles to defrost the coil. At the bottom of the evap coil is a tray. It's shaped like a funnel. The condensate drains into the center of the tray..... down a hose on the back or thru the back wall to a drain pan under the unit where the water collects and the heat evaporates it.

It's very common to have that drain line get clogged with algae and other crap. When the line is clogged, the tray fills up and water runs all over the place. It will come out the damper. Usually it runs down the inside back of the fridge. Since you're unthawing the unit..... take the cover off the evap coil in the back of the freezer. It may be clips. It may be screws. Look at the coil. Check out the tray below it. Usually once the fridge unthaws thoroughly .... the drain may also unclog. Sometimes partially. It's important to flush it out with a cup of very warm water and 1/4 cup of bleach. Do that twice. No more than that as the pan in the bottom could overflow.

That's an older unit and the exploded views aren't terribly clear. The evap coil is shown in the [evaporator area] tab in the manual below.
Sears Parts Direct - parts and views