Once a year or more depending on the dust that builds up in your kitchen you should clean the evaporator coils on your refrigerator.
Evaporator coils are part of your cooling system. When your refrigerator freon compressor squeezes the coolant to send it into your refrigerator compartment for cooling the coils let off the heat.
The more dust that builds up on the coils the harder it is for your refrigerator to work.
The job is relatively easy to do an only takes a few minutes to perform.