Kind of OT but not completely - bimetal question

[JohnCT]

Can bimetal switch show a drift down in "on" temperature, or is the failure mode of bimetals pretty much binary good/bad?

For full disclosure, the reason this is OT is because the bimetal switch in question came out of an old Whirlpool refrigerator that I suspect had the defrost timer not running/working because the bimetal wasn't closing consistently. It would reliably click on whenever I hit it with freeze spray and click off at room temperature, but I don't know if the freeze spray was just a lot colder than the freezer evap coil. In any case, it seems to have resolved the issue, but because this has been an ongoing issue with this particular fridge, I'm not so sure.

John

 

[Fitter30]

Any bimetal control starts working when it is made. Can sit in a warehouse or on a truck temperature is changing. Using a freeze spray and room temp on a control really doesn't mean a thing because there extemes. Controls are made to tight specs. The contact can be sticking or not making good contact. Most fridges used a timer for defrost located under the front kick grill has a knob or screwdriver slot to advance the timer.