Disclosed is a method for evaluating a non-measured operating variable in a refrigeration plant, which can be derived from at least one signal which is sensed at specific points in time, enabling early recognition of errors. An error indicator is formed by means of the following steps: a) the error indicator is set to a specified value at a first moment in time; b) a sum if formed from the error indicator of a predetermined earlier moment in time and a first variable derived from an estimated value for the operating variable taking into account at least one signal-dependent variable; c) the error indicator is set to the value of the sum if the sum is greater than the specified value, and set to the specified value if the sum is less than or the same as the specified value.