Hi, I know there is a sticky for problems like this but it's difficult to pinpoint the exact problem. I have a maytag msd2572veb01 that is currently cooling refrigerator side at approx 50 degrees. About 6 weeks ago I took out the back panel of freezer and the coils were completely frozen over. I got rid of all the frost and it started cooling properly up until the other day.

It sounds like it'll be narrowed down to a few things:

Defrost control board
Defrost thermostat
Defrost heater

Before I start purchasing these, how can I test which is the real problem? Most things I've read suggest the control board is bad...but it's the most expensive piece and I don't know for sure it's the reason.

What's the best way to determine root cause?

Thanks
Jonathan