This paper examines the available heat of internal combustion diesel engines for activating automotive air conditioning systems with an absorption refrigeration cycle using ammonia-water pair. Firstly, an exergetic study was carried out of both the engine and absorption cycles working together, to assess the technical feasibility of using this system for air-conditioning vehicles for public transport. The modeling and simulation were developed through algorithms on the Engineering Equation Solver platform, taking into account mass balance, the first and second laws of Thermodynamics, identifying tailings and losses in the thermal system. The simulation of the internal combustion engine is modeled for the flexibility of biodiesel, to provide an energy and exergy analysis depending on the type of fuel used in the engine. It was possible to analyze the effects that variations in the engine exhaust gases can cause in the refrigeration cycle and to determine the thermodynamic state in the refrigeration cycle, the behavior of the coefficient of performance, refrigerated power and exergy distributed in function of the variation in the condensation and evaporation temperature, and the conditions of gases in the generator.