An air cooling system is provided for cooling ambient or recirculated air. The system includes a compressor receiving ambient air, and a first heat exchanger receiving pressurized air from the compressor. An expander receives warm air from the first heat exchanger. A second heat exchanger receives cold air from the expander. The second heat exchanger also receives supplemental ambient air, and is structured to utilize the cold air to cool the supplemental air and provide mixed cool air. The system cools and dehumidifies the supplemental ambient air to prevent unwanted stratification and condensation.