A method of controlling an in-wall dehumidifier is disclosed. The method includes setting the dehumidifier to a defrost mode if the dehumidifier has been operating in a dehumidifying mode for less than a predetermined amount of time and a measured evaporator coil temperature is less than a first evaporator coil temperature set point. The method further includes setting the dehumidifier to the defrost mode if the dehumidifier has been operating in the dehumidifying mode for equal to or greater than the predetermined amount of time and a measured evaporator coil temperature is less than a second evaporator coil temperature set point that is higher than the first evaporator coil temperature set point.