Every 3 weeks our refrigerator fan freezes and starts making noise,

Hi @samsungbonnie ,

What is the model number of the refrigerator?

It sounds as though the evaporator fan in the refrigerator is being frozen over due to a problem with the auto defrost in the refrigerator compartment.

Given that you say that it occurs in the refrigerator compartment, your model is probably one that has two evaporator units. One in the freezer and one in the refrigerator whereas a lot of side by side refrigerators only have the one in the freezer compartment.

Search online for Samsung (insert refrigerator model number) parts to find suppliers that may have parts diagrams that can verify this. (partselect.com and searspartsdirect .com are two that usually do have these)

Also search for Samsung (insert refrigerator model number) service manual. Sometimes you can be lucky and find the service manual (for free) and this details how to run diagnostic tests which may also help to know what is happening

Defrost problems can be caused by a faulty defrost heater, located beneath the evaporator unit, a faulty defrost thermostat which is used to signal when to end the defrost cycle, a blocked drain which leads from under the evaporator unit to the evaporator pan under the freezer compartment near the compressor unit or a faulty control board which initiates the defrost cycle.

Not sure how often a refrigerator defrost cycle occurs but a freezer defrost cycle occurs approximately once every 10 hours to melt the ice build up on the evaporator unit allowing it to drain away. After 10 hours of normal operation there really is not that much ice build up anyway or not enough to freeze over a fan which is located near the evaporator.