On Monday, February 11, 2019 at 5:26:47 PM UTC-5, Rod Speed wrote:
Davej wrote
Rod Speed wrote
Davej wrote

Can anyone explain the internal circuit of a 3-pin
refrigerator thermostat such as a WDF-18 ? Thanks.

https://www.amazon.com/s/ref=nb_sb_n...tor+thermostat

One terminal is the common. That is connected to one
or other of the other two terminals depending on
whether the temperature is above or below the set point.

Oh, so what would a refrigerator need to apply
power to when it shuts off the compressor?

It doesnt, its just the way thermostats are usually done.

Not likely, I bet there is a wire connected to all three terminals.
It may be part of a design so that the defrost heater is only powered
when the compressor is off.




You see the same thing with oven thermostats too.





Its more obviously useful with room thermostats.

It's not useful there, of all places. I never had a thermostat that
was more than a simple on/off switch for a home heating system. Some
have two stages, but that's another story.