TEMPERATURE, HUMIDITY AND VENTILATION CONTROL: The Temperature Humidity and Ventilation System (THVS) conditions the cabin atmosphere to provide a shirt-sleeve environment for the crew. It does this by circulating the cabin air to provide good gas mixing, by removing excess heat to keep air temperature within the proper range, and by removing excess moisture to keep humidity in the proper range. This system uses a single condensing heat exchanger, two non-condensing heat exchangers, and circulation fans to achieve these goals.