This paper presents an experimental study on the application of hydrocarbon mixtures replacing HFC-R134a in current automotive air conditioning system. The study will evaluate the fuel consumption, cabin temperature, coefficient of performance (COP) and cooling capacity of the air conditioning system at various internal heat loads and vehicle speeds using hydrofluorocarbons refrigerant (HFC-R134a) and hydrocarbon refrigerant as the working fluid of the compressor. Both refrigerants will be tested in actual petrol engine vehicle on the roller dynamometer to simulate actual vehicle on level road. The experiments are conducted at the same surrounding conditions. Heat and weight of human is simulated by lamp and sand bag acting as the passenger load. Temperature is taken at 4 points inside the vehicle cabin to analyze thermal comfort. The tests have been performed by varying the vehicle speed; 50, 70, 90 and 110 kph, and number of passenger; 1, 2, 3 and 4 people, at temperature set-point of 21°C. The result shows that the hydrocarbon mixtures indicate the positive improvement of the system compared to HFC-R134a.