Thank you for reaching out to us. I find this post written in Chinese characters and I just used google translate for me to understand. So please bear with me, and I hope I understand your question correctly.
Regarding to your concern, there are customer in the past who wants the same operation with yours. Either they only need cooling mode or heating mode only. For this type of application, we suggest implementation of diode in series with the TEC module in such a way that it will allow the desired mode, and block the other.
I hope this helps and work with your implementation.