Method and system for detecting leaks in the refrigeration units of a fuel cell stack

The method involves forming a cooling unit (2a,2b) by contact of two contact surfaces of plates (4,6). A coolant space (8) for cooling agent is formed between the two plates. A gas space (12,14) is formed between each plate and the respectively adjacent electrolyte electrode assemblies (10a-10c). The supply of oxygen and hydrogen feed to the gas spaces is interrupted. The air is passed into the coolant space and voltage between two cooling units is measured. The sign of the measured voltage is considered with respect to location of the leak. An independent claim is included for a system for detecting leaks in between electrolyte electrode assemblies arranged cooling units of fuel cell stack.