An air‐cycle air conditioning system, using a typical automotive turbocharger as the core of the system, was designed and tested. Effects on engine performance were kept to a minimum while providing the maximum amount of cooling possible and minimizing weight and space requirements. A test stand utilizing shop compressed air was developed to measure component performance. An unmodified automotive turbocharger was tested initially as a baseline in a Reversed‐Brayton Cycle air cooling system. Once the baseline was established, another aircycle machine, assembled from commercial turbocharger components chosen individually to optimize their performance for cooling purposes, was tested to improve the overall cycle efficiency. Finally, once the air‐cycle air conditioning system was optimized, it was tested on an engine to simulate more realistic operating conditions and performance. The shop‐air test stand experiments showed a peak dry‐air‐rated (DAR) coefficient of performance (COP) of 0.38 and a DAR cooling capacity of 0.45 tons for the baseline turbocharger, and a peak DAR COP of 0.73 and DAR cooling capacity of 1.5 tons for the optimized system with a modified turbocharger. The on‐engine testing was limited due to a thrust bearing failure in the ACM. However, the data collected at lower engine load and speed indicates a DAR COP of 0.56 and a DAR cooling capacity of 0.72 tons. On‐engine testing was planned to include operating points where the stock turbocharger was utilizing turbine‐bypass to limit boost pressure. While it wasn't possible to continue testing, it is expected that DAR COP and cooling capacity would have increased at higher engine load and speed, where turbine‐bypass operation typically occurs.