| 摘要 |
PROBLEM TO BE SOLVED: To reduce the level of sound which is generated when a baffle plate comes into contact with a closure plate at a given position in its movement from an intermediate stop position to the given position. SOLUTION: In starting a stepping motor 59, a large amount of starting electric power is fed to the stepping motor 59 to start the stepping motor 59 rapidly and smoothly, while in stopping the stepping motor 59, a large amount of stopping electric power is fed to the stepping motor 59 so as to make a baffle plate 54 assuredly close or open a cold air inlet passage. Once the stepping motor 59 is started, a steady state operation electric power which is smaller than the starting electric power is fed to the stepping motor 59 so as to reduce the level of sound caused by the motor 59 during the steady state operation. |
