defrost thermostat specs

I’m trying to test my defrost thermostat. It’s supposed to open when warm; close when cold, right? It’s closed (zero resistance, continuity) all the time.
Do the following specs indicate what “cold” and “warm” should be? If it’s closed all the time do I need to replace?

specs are L140 - 30F.
Manufacturer’s Number: WR50X10068 Made by GE
Item Number: AP3884317

They rarely short, stick it in the oven and verify it opens when above the cutoff temp.

Does “L140” indicate a cutoff temp of 140F? Do the specs even indicate the cutoff temp? Anyway, you seem to be saying that it’s OK if it has continuity at room or body temperature, rather than having to frost up (“30F”?) before closing the circuit . Is that right?

Pardon my lack of immediate comprehension. I find this a bit confusing and don’t want to install a bad part.