冷凍片運作

我有一冷凍片一邊是吸收熱一邊是放冷，但係如果將電源正負掉轉熱變冷而冷變熱。

Usually, manufacturer have a making on it.
If not, you can power it and feel the cooler side.

2008-12-02 15:27:13 補充：
One condition is you connect the wire properly: Red for +ve, Black for -ve. Also, the cool side can be a heater by reversing the power polarity. There is no restriction of the the polarity so that Peltier device can use as a heater or cooler at the same time.