Problems with a freezer's condenser or compressor usually require the services of a professional repairman, according to home maintenance website DoItYourself.com. However, the problems caused by defects in these mechanisms often look similar to problems with user-serviceable parts of the refrigerator.
Problems that may require a professional repairman include a refrigerator turning on and off repeatedly or running constantly without ever becoming cold. Refrigerators that sweat may require a professional to repair the mullion heater that controls condensation on the refrigerator. It is advisable to have a professional replace the refrigerant in a refrigerator, due to the expense and legal complexities involved in disposing of used refrigerants.
Because of the complexity of a refrigerator's mechanisms, problems that truly require a professional repairman are difficult to separate from problems that owners can fix themselves without going through a process of elimination. For example, while a defective compressor sometimes leads to a freezer turning itself on and off rapidly, these problems can also be caused by a blocked condenser fan or dirty compressor coils as well. Both blockage of the condenser fan and dirty coils can be addressed by cleaning the affected parts. It is advisable to research potential causes of a freezer issue and exhaust all of the possible solutions before calling in a repairman to avoid unnecessary costs.