The 'air conditioners' that the Apollo astronauts were seen carrying with them to the transfer van during launch day were Portable Oxygen Ventilators. The POV's pre-oxygenated the astronaut and purged the nitrogen from their body, which was needed during altitude testing/training in the spacecraft as well as for launch to prevent 'the bends.' In addition to providing breathing oxygen, the POV kept the space suit pressurized, dehumidified and cooled as well as helped remove moisture from the body. There were different models of the POV, but they generally lasted approximately 30 minutes and after the astronaut was on his way in the transfer van to the launch pad, he would be connected to a fully charged POV and then eventually connected to the Command Modules suit circuit once inside the spacecraft. There was also an open-loop ventilator that was similar in operation to the POV, except used only for cooling when the helmets & gloves were off.
