Experimental tests were conducted on a parallel flow condenser with HFO-1234yf as the working fluid on an AC system bench. This refrigerant is being considered as an alternative refrigerant for mobile air conditioning systems (MACS) to address the global warming concerns. A condenser from MY 2008 medium sized sedan was used for this investigation. Tests were first conducted with R-134a and were then repeated by maintaining each test condition by changing the working fluid from R-134a to HFO-1234yf. The refrigerant was used as “drop-in” refrigerant in the existing system. All original OEM parts were used with the alternate refrigerant. Same TXV set-point was used with HFO-1234yf. Detailed test results have been presented in this paper.