What do I do when the inside back wall keeps freezing over?

Hi @brynluvz

What is the model number of the refrigerator?

It seems as though there is a defrost problem.

Instead of the evaporator unit at the back of the freezer compartment behind a panel, being defrosted once every ~10 hours, the ice is building up which causes the evaporator fan which blows the cold air into the freezer and refrigerator compartments to ice over and stop. This effectively means that the refrigerator won’t be as cool anymore nor the freezer compartment.

The cause of defrost problems (in no particular order) can be a faulty defrost heater, a blocked drain pipe, a faulty defrost thermostat or a faulty defrost timer or control board.

The defrost heater is located under the evaporator unit and when the refrigerator goes into the auto defrost cycle the heater is switched on to melt the ice build up on the evaporator coils. At the end of the cycle the heater is turned off until the next cycle occurs ~10 hours later.

The drain pipe leads from under the evaporator unit to the evaporator pan below the compartments near the compressor unit. If the drain pipe is blocked, no defrost meltwater can flow to be evaporated in the pan and when the defrost cycle is over the backed up meltwater refreezes and the ice continues to build. With a lot of models the pipe has a J curve just above the evaporator pan and this is where a blockage can occur.

The defrost thermostat operates when the temp in the freezer reaches ~29 F during the defrost cycle. This signals the defrost timer (or control board) to end the defrost cycle by turning off the heater and to restart the compressor to cool the compartments back down again. If the defrost thermostat is faulty the heater may not operate (depends on how it is configured) or perhaps the time allowed may be too short for any effective melting of the ice.

The defrost timer or control board (depends on model) controls when the auto defrost cycle occurs and in conjunction with the defrost thermostat, for how long.

Usually a defrost cycle takes about 20 minutes to complete. During this time both the compressor and the evaporator fan are switched off and the heater is turned on.