Kenmore Elite model # 795.77564600 refrigerator stops cooling; display on left side door reads ER FF

This is an error code that pertains to the evaporator motor but could also be the main board.
If the evaporator motor is running, the main board will probably need to be replaced.
It could be a wiring problem but it's not very likely.

If the motor is not running, some voltage checks will need to be made, at the motor and board, to determine which component has failed.
These checks require a meter and can be difficult to make, even for a technician.

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I feel like a voice in the wilderness...the error FF indicates that the freezer fan is not running...this is the fan that circulate cold air around both the freezer and the fridge...here is MY reason for typing this...the freezer ices up due to excess humidity. In my case the mullion, that fancy innovations that allows you to open ether fridge doors was not operating. This meant that there was often a gap between the fridge doors and this allowed air and moisture to get in. Hence the ice build up. Check your left hand fridge door and see if the mullion is moving into place when the fridge door is closed. If not realign the door (UPWARDS) using the cir-clips that came with the unit until it works properly...

As I said in another post, the problem causing the ice buildup is humidity in either the fridge or or the freezer.