An pulse electro thermal defrost evaporator system has multiple refrigerant tubes formed from an electrically conductive metal and connected in parallel for refrigerant flow. These tubes are, however, connected electrically in series. A controller is capable of detecting ice accumulation and connecting the tubes to a source of electrical power for deicing when it is necessary to deice the tubes. Embodiments having a manifold having multiple conductive sections insulated from each other are disclosed for coupling tubes electrically in series. Alternative embodiments with a single, long, wide-bore, tube are disclosed, as are embodiments having an evaporating pan coupled in series or parallel with the tubes, and embodiments with thermal cutoff and electrical safety interlocks.