My GE french door refrigerator freezer section is not cold enough (~20F, but set to 0). Fridge section is fine (holds at 37F). In running the tests, the fans and thermistors seem to be reading correctly. When I exposed the freezer evaporator coils, there was an ice block in the upper right corner, but the heater works. I manually defrosted the block, but it didn't help. The evaporator coils DO NOT have a light frost on them (only on the supply tube). After reading other posts, I believe this means I have a sealed system leak.
Is there a definitive check to know if it's the sealed system (I don't have refrigerant equipment)? I had to replace the inverter and condenser fans about a year ago. Is there any chance it could be the inverter again? Is there anything else it could be? If it's a sealed system leak, it seems like I should get a new fridge, but I hate to throw this one in a landfill. It's only 7 years old.
I'd appreciate any help.