This　study　has　been　carried　out　to　investigate　the　feasibility　of　using　the　photoelectric　method　for　defrost-control　in　refrigeration　equipments.　The　new　method　originates　from　the　principle　of　the　photoelectric　conversion.　Photoelectric　sensors　were　emplaced　on　the　cold　finned　heat　exchangers　in　natural　convection　regimes.　Three　frost　and　defrost　cycles　were　performed.　During　these　cycles,　the　photos　of　frost　were　taken　by　the　microscope　and　the　height　of　frost　was　measured　on　the　photos.　At　the　same　time,　the　output-voltage　of　the　photoelectric　sensor　was　monitored.　The　experiment　results　present　that　the　photoelectric　signals　experience　three　different　periods　during　the　frost　process.　Further　more,　the　signals　present　two　desirable　characteristics,　namely,　＇binary＇　and　＇linear＇.　These　characteristics　indicate　that　the　photoelectric　method　is　feasible　to　solve　the　problem　of　mis-defrost.　Copyright　©　2009　by　ASME.