JPH0311922B

PURPOSE:To prevent the invasion of contaminated air and control the humidity of a ride room to be appropriate, by providing a gas sensor and a humidity sensor to detect the contamination of the air outside the ride room and the humidity of the air in the room. CONSTITUTION:First in condition judgment processing, a microcomputer 15 compares the output of a gas sensor 13 with a preset degree of contamination to judge whether the air outside the ride room of a vehicle is contaminated. Second, the microcomputer 15 calculates, on the basis of the output of an outside air sensor 10, such humidity of the ride room that the window pane of the vehicle begins to collect moisture. The microcomputer 15 then compares that reference humidity with the output of a humidity sensor 12. In output judgment processing, the microcomputer 15 acts to operate an inside and outside air changeover means 2 and drive dehumidifying coolers 4, 5 if the outside air is contaminated and the humidity of the ride room is high. In that case, the coolers 4, 5 may not be driven and an indicator lamp 22 may be lit to warn that the outside air is contaminated and the humidity of the ride chamber is high.