bump...anyone have any ideas or comments on this one? moving everything downstairs and manually defrosting is getting very very old!!

Amana bottom freezer

Model# ABB222ZDES
Serial# 11263413GR
No ice maker installed, fridge was bought without it

Weeks back I noticed that the fresh food part of the fridge was not as cold as it should be...looking at the coil in the back of the freezer I noticed that it was all iced up....I took everything out of the fridge, unplugged it and manually defrosted it...checked the drain for blockage and emptied the catch pan under the compressor...I plugged it back in and it ran fine for a few weeks...I figured the freezer door was left open for a significant amount of time and that caused it to freeze up....I was wrong, it did it again...

the heater coil checked out good with a meter so I replaced the defrost thermostat and the freezer thermistor...the unit ran fine for a few weeks and just recently froze up again...

I cannot find a defrost timer listed with the parts or on the unit...which leads me to believe that it is built into the electronic control board...if someone could verify that it would be much appreciated...

so my question is....should I replace the control board and hope that it was an issue with the timer? or is there something else I’m missing...

Thanks in advanced for any comments, ideas or advice...