In order to control exhaust gas flow and heat transfer in the generator element of the absorption refrigeration system, a microcontroller based control circuit was developed. The system variable used as a reference for the control system was the generator temperature (TG). A proportional-integral (PI) control algorithm was implemented in order to determine the opening level (from 0 to 100%) of valves V1 and V2 necessary to maintain the generator temperature fixed at a pre-defined reference value. The PI action A (defined in terms of valve opening percentage) is calculated according to: