This is a popular and inexpensive unit for laser cooling. I like to operate under 20 degrees but over 20 the cooling fan comes on. If the room are temperature is let's say 24 Deg then no matter how long you run it, it stays at 24.
So I put a PC radiator just before the inlet and dunk the radiator in ice water. The room keeps it above 20 and the ice tries the pull it below 20 and the room wins.
Solution is to turn the fan off. I just wired a switch into one leg of the leads to the fan. Now I can cool it down to 15 degrees in warm weather

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