Apparatus for controlling refrigerator defrost apparatus

Claim 1

Apparatus for controlling the operation of refrigerator defrost apparatus comprising, means for continuously sensing the temperature of the evaporator coil of the refrigerator, means for conTinuously sensing the temperature of a storage space of the refrigerator, and means controlled by said temperature sensing means for initiating operation of said defrost apparatus when the difference between said two temperatures exceeds a predetermined value and, a selected one of said temperatures is less than a predetermined temperature, said means for initiating defrost including an electrical control circuit comprising two normally turned off electronic switches arranged in series with means operable, when energized to initiate operation of said defrost apparatus, and including means responsive to said two temperature sensing means to cause one of said electronic switches to turn on when the difference between the two temperatures sensed thereby exceeds said predetermined value, and vice versa, and means responsive to a selected one of said temperature sensing means to cause the other said electronic switch to turn on when the temperature sensed thereby is less than the said predetermined temperature, and vice versa.