A fuzzy inference system (FIS) and an artificial neural network (ANN) were used for diagnosis of the faults of a vapor compression refrigeration experimental setup. A separate EIS was developed for detection of sensor errors. The fault estimation error of the FIS and ANN were evaluated by using the experimentally obtained sensor data. Separate FIS estimated the system faults and detected defective sensors in all test cases without any error. Levenberg Marquart (LM) type ANN algorithm was implemented to diagnose the system faults. Scaled conjugate gradient (SCG) and resilient backpropagation (RB) network type were also used to compare performances with the estimation of the LM algorithm. The LM type ANN estimated all fault conditions accurately in the test cases never observed before. The study demonstrated that the EIS and ANN could be used effectively to estimate the faulty conditions of the vapor compression refrigeration system. (C) 2014 Elsevier Ltd and IIR. All rights reserved.