Abstract: A vacuum system includes at least one cryopump; sensors associated with the cryopump, each of the sensors being configured to sense an operating condition of the cryopump; and diagnostic circuitry configured to receive signals sampled from the sensors. The diagnostic circuitry includes a diagnostic model of the cryopump, the diagnostic model being derived from historical data of a plurality of cryopumps of a same type operating over a plurality of regeneration and servicing time periods and being configured to relate values of the sampled signals from the at least some sensors to a probability of the pump failing within a predetermined time. The diagnostic circuitry is configured to apply the sampled signals to the diagnostic model and to determine the probability of the at least one cryopump failing within a predetermined time from an output of the model.