Customer Questions and Answers for Refrigerator Air Diffuser by Whirlpool

Hello Shawna, This sounds like the unit is short cycling. I would first try replacing the defrost thermostat WPW10225581. The unit should also sit idle for several minutes after the defrost thermostat opens to allow time for the melted frost to make its' way down the defrost drain. I would also check for any possible air leaks which would add room humidity which would cause excessive frost buildup. It is doubtful that the diffuser would have anything to do with the frost accumulation.