Hi @coils ,
What is the model number of the fridge?
Things that could be wrong depending on model, not in any order:
Defrost heater open circuit. _ not operating during the defrost cycle to help melt the ice formed on the evaporator unit (located in freezer compartment), allowing ice to build up. During defrost cycle the compressor and evaporator fan is stopped (occurs every 6 -12 hours depending on manufacturer) and the temperature in the freezer is allowed to rise to nearly 32 F (0 C) to melt the ice formed. The heater is switched on to speed up the process as you don’t want the food to even begin to thaw. The defrost cycle lasts about 20-30 minutes
Drain tube blocked - this tube leads from the freezer compartment to the evaporator pan below the fridge and drains the meltwater from the defrosting evaporator unit during the defrost cycle. If the drain is blocked water can’t drain and ice builds up.
Defrost thermostat faulty - this controls the temperature during the defrost cycle by operating when the temperature reaches 32 F (0C) and signalling to the control board to start the compressor and evaporator fan again to cool down the fridge. The reason for this is to not damage the evaporator unit by allowing it to get too warm.
Control board faulty, this controls the defrost cycle (and all the other cycles as well obviously).
If you search online for Amana (insert full model number) parts you will find suppliers - example only insert model number in search box who have parts diagrams showing where the relevant parts are and also sometimes offer “suggestions” as to what parts are the most likely reason for the symptoms being exhibited by the refrigerator.