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A multivariable fuzzy controller was developed and implemented for the regulation of the secondary fluid temperature in a chiller using both the rotation frequencies of the pump and the compressor as manipulated variables. Its performance was measured using the integral of time-weighted absolute error ( ITAE) index and the energy consumption. The proposed control strategy proved able to adequately control the chiller in all experiments. For comparison purposes, similar experiments were carried out with fuzzy control strategies in which only one variable was manipulated at a time. Comparing the performance of the proposed controllers with the fuzzy single input-single output controllers for regulatory control, a mean percentage reduction of at least 88.5% was observed in the ITAE. Good results were also observed in control effort and energy consumption. Besides, the implementation of the control strategy was quite simple. Practical Applications Refrigeration systems are of fundamental importance for food conservation. Besides, to maintain the temperature into a narrow range needs an efficient control system and implies energy consumption and equipment wear. The use of a fuzzy controller with two manipulated variables to regulate the secondary fluid temperature has proved to be an efficient control configuration. Desirable characteristics like small or no overshoot, reduced control effort were achieved by the proposed multivariable fuzzy controller. Therefore, this proposed strategy is a valuable alternative to control processes that require strict variability or long periods of operation without stopping. [ABSTRACT FROM AUTHOR]