Fridge is cold one week, warm another. Help please

Hi,

What is the model number of the fridge?

Check that the evaporator fan in the back of the freezer compartment (inside behind a panel at the back, not the fan outside that is the compressor fan) is not getting iced up and prevented from operating. Is it running at all when the fridge seems warm (can you hear it as it will stop when the doors are open?

If it is iced up that is why the freezer is cold (ice buildup on evap unit in freezer behind panel and perhaps freezer compartment itself looks frosty, like an old fashioned ice chest) and the fridge is warm because fan cannot push cold air throughout fridge.

Ice build up occurs either because during defrost cycle (which is a timed event - occurs once every 8-12 hrs - maker dependent)1. defrost heater is faulty and all ice is not melted, therefore gradual build up as every time more ice is added and not melted in defrost cycle 2. defrost thermostat is faulty 3. control board is faulty.

Defrost cycle lasts about 20-30 minutes, temp in freezer rises from 0F (-18C) up to 34F (2C) to allow ice to melt, helped by heater. Then compressor started to drive temp back down to required setting. Of course there are thermostats for the fridge and freezer to monitor the temps to either maintain the compressor running or to turn it off this is done by the control board.

Also there are no attached pics or at least I cannot see any.