A method for detecting a faulty air handler of a heat pump appliance is provided. The method includes activating a compressor of the heat pump appliance and deactivating the compressor of the heat pump appliance at a predetermined period of time after the step of activating. The method also includes determining temperatures of a fluid treated by the heat pump appliance and refrigerant in the heat pump appliance and requesting replacement of the air handler of the heat pump appliance if various conditions associated with the temperatures of fluid treated by the heat pump appliance and refrigerant in the heat pump appliance are met.