Martin Thermal Engineering, Inc. investigates failures of large and small refrigeration systems, including those that store pharmaceuticals or other high-value contents. Components at the root of the failure sequence can include compressors, condensers, evaporators, expansion valves, pressure or temperature transmitters, insulation, and seals. In large, multiple-compressor industrial freezer systems, ice plugging can result from ineffective defrost, which can be caused by inadequate humidity control or pooling of liquid refrigerant in evaporator coils. Design and maintenance of enclosure seals and fire protection systems in large freezers can be technically challenging.