The thermostat is dead in my strange¹ fridge with no replacement parts. I posted about the mystery component before.
There is a metal plate that appears to sandwich a single small loop of refrigerant (guessing!). Mounted attached to the backside is a coil with a ground and two wires marked to handle 220v. One of the leads connects to the LOAD wire on house mains and the other to the (now broken) thermostat.
I can only imagine that it’s a heating element for defrosting (as suggested). But I struggle a bit with that theory because I’m surprised the fridge would ever get cold enough to justify defrosting.
Anyway, I wired the mystery coil directly to mains and left it for 10 min or so. The temp of the metal plate did not feel any different. Is that expected? Metal is naturally cold at room temp and that did not change.
I would like to understand it because I cannabalised a simpler t-stat from another fridge. The t-stat has no connector for whatever the mystery component is.. it’s just a switch that connects two wires. I don’t know if I should just omit the mystery component, or if I should wire it in series with the new t-stat, or keep it attached to the old broken t-stat and wire that in parallel to the new t-stat.
¹ I say strange because there is no freezer-fridge vent. So the fridge is independently cooled.
If this is indeed a non us fridge, this is probably a heat pump fridge. Compressor in the back should confirm it. The plate probably allows the coolant to expand and thereby cool down inside the fridge.
It’s a non-US fridge. But I’m curious about you calling it a heat pump fridge. The one thing all fridges worldwide have in common is using a compressor for refrigeration (or so I thought), which is the same as a heat pump but stressing that the goal is to cool rather than heat a space. Are there US fridges that do not use a compressor?
The only exception I'm aware of to all fridges having a compressor is propane models. There's a vessel they heat to build pressure in its place, and sometimes an (incredibly inefficient) electric mode where a resistive heater acts on that vessel. They're very uncommon, pretty much exclusively used off-grid, and in no way specific to the US.