In this paper, a new set of algorithms has been developed to detect low charge fault for single compressor non-critically charged refrigeration system for both frozen and perishable goods. A mix of field units' data and experimental data were used to build the detection algorithms. Multiple detection algorithms were devised based on the operation modes. The system operates in multiple distinctive modes. Each mode has a defining characteristic. The used data includes several healthy and predefined low charge defected systems which gave us a prediction of the loss of charge percentage in different operational modes. This prediction provides us with a good knowledge of the system performance and operation.