The present invention relates to a defrost system for defrosting components on which frost is formed, where the defrost system comprises at least one compressor, which has a hot gas outlet, which is connected to condensing means, from where primarily liquid refiigerant is connected to pressure reduction means, from where the flushing refrigerant is led towards evaporator means. The object of the invention is to perform effective defrosting by a defrost system. This can be achieved if the defrost system is formed as an independent cooling system, where the condensing means are transmitting heat to the defrosting components, where the evaporator is cooperating with external cooling means or from the refrigeration system, enabling defrost without deflecting the main system. It can hereby be achieved that the defrost system can operate completely independent of another refrigeration system. All negative effects with traditional defrost operation of refrigeration systems are overcome by means of this solution where the defrost system operates as a system without any influence from the refrigeration system.