Due to ecological problems like Ozone depletion and Global warming certain refrigerants like R-22 have to be replaced. HCFC's (Hydro Chloro fluoro carbon) have been identified as the prime foremost cause of Ozone depletion. Driven by 1992 amendment to the Montreal-Protocol that calls for the phase out of HCFC's. HFC's (Hydro fluoro carbon) are substantially less damaging to the Ozone layer than HCFC's. Several refrigerants have emerged as substitutes to replace R-22, the most widely used Fluoro carbon refrigerant in the world. These include the environmentally friendly hydro carbon refrigerants such as R134a, R410A, R407A and R407C. In this present work problem of R-22 phase out in air conditioning application is addressed. The main objective of the project is Performance analysis of an window air conditioning system by using three refrigerants like R-22, R407C and R410A with different capillary pitches. In view of this it is proposed to carry out a number of experiments on window air conditioner of capacity 1.5 TR using R22, R407C and R410A by varying the capillary pitch. Further it is proposed to make a detailed analysis and comparison of the performance of these refrigerants at various pitches for an window air conditioner. From the results it is evident that the refrigerant with R410A with a capillary pitch of 18mm gave the best Coefficient of performance to retrofit an window air conditioner working on R22. © IDOSI Publications, 2014.