I ordered and received a defrost thermostat and wanted to test it before putting it in. The circuit is open (infinite res) out of the box at room temp. I froze it with spray just to see if it was backwards, and it stayed open. I put it under a heat lamp and at 84F it stayed open.

Then I returned it because I thought it was bad. I received a new one and it tests the same way. I was assuming that the thermostat should be open until it gets too cold, then should be closed, to turn the heater on. Am I mistaken?

I apologize for writing my original question backwards. It should have said:

I ordered and received a defrost thermostat and wanted to test it before putting it in. The circuit is closed (zero res) out of the box at room temp. I thoroughly froze it with spray until it was entirely covered with frost, and it stayed closed. I put it under a heat lamp and at 84F it stayed closed.

I returned it because I thought it was bad. I received a new one and it tests the same way. I was assuming that the thermostat should be open until it gets too cold, then should be closed, to turn the heater on. But these are always closed. How can I test if the open/close is working?

Snap, I bought the wrong part. I was going by the 37TV31 stamped on it but I guess more than one thermostat uses that. The one I got was WR50X10068 instead of 10006. It says L140-30F and it does open if I heat it to 140 and closes when it cools down.

Thanks, I will have to exchange it for the correct part.

i also just bought the DA47-00243K bimetal thermostat for my samsung. i got it in the mail today and it is closed when it is at room temp. they are sending a replacement, but maybe it will also be closed at room temp. it must be a serious lemon?!