Most existing Fault Detection and Diagnostic (FDD) methods for chillers are primarily tested and evaluated in a controlled laboratory environment. The controlled laboratory environment is usually configured and installed to satisfy the requirements of the FDD methods and therefore contain rich data sets. However, some measurements required by the FDD methods may not be commonly available on the field chillers. Therefore, field demonstrations and commercialization of chiller FDD is a big challenge since many practical issues must be addressed. In this study, a decoupling-based FDD method which can deal with multiple simultaneous faults was fully implemented online and evaluated in the field test environment. A step by step process of implementing the evaluated FDD method for the real application is described to aid readers to apply and use the method. Several occurrences of multiple simultaneous faults were found on the test chiller. The field test results show that the decoupling-based FDD method has potential to be incorporated within commercial FDD products or embedded into the control system onboard the chiller to monitor the health of the chiller's operation. (C) 2014 Elsevier B.V. All rights reserved.