this post was submitted on 11 Nov 2025
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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.

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[–] diyrebel@lemmy.dbzer0.com 1 points 1 week ago* (last edited 1 week ago) (1 children)

I would really be hard-pressed to get a pic of the Zanussi 19/4 that’s worth 1k words in this situation. The backside of the plate is inaccessible. Every time I pull the plate forward to get an eyeball back there I worry that a tube carrying coolant will break. Not sure how many times I can bend it but I’ve bent it dozens of times already.

I found the manual online somewhere but it’s almost useless. Perhaps this excerpt is useful though:

Defrosting

Frost is automatically eliminated from the evaporator of the refrigerator compartment every time the motor compressor stops, during normal use. The defrost water drains out through a trough into a special container at the back of the appliance, over the motor compressor, where it evaporates.

It is important to periodically clean the defrost water drain hole in the middle of the refrigerator compartment channel to prevent the water overflowing and dripping onto the food inside. Use the special cleaner provided, which you will find already inserted into the drain hole.

The freezer compartment, however, will become progressively covered with frost. This should be removed with the special plastic scraper provided, whenever the thickness of the frost exceeds 4 mm.

This is a pic of the front side of the metal plate: pic of metal plate in fridge compartment

There are two white wires and a ground wire going from the blob on the right to behind the plate. The wires run in a loop inside some coil of tube.

Below the plate is a V shaped trim on the inside back wall below the metal plate. I guess water drips off the plate into the V and through a hole that leads to a drip tray on the back of the fridge. I guess I would expect water to condense and drip.. but maybe it needs help. Maybe the mystery component that I can’t get a pic of is a heating element. But I don’t get why the plate does not get warm when hotwired.

Maybe 2 things are broken.. maybe the t-stat broke and perhaps the heating element was already broken. I’m tempted to ignore (what I think is) the heating element.

[–] bitfucker@programming.dev 3 points 1 week ago (1 children)

Oh, it is a big plate. Probably not a thermal cutoff then

[–] diyrebel@lemmy.dbzer0.com 2 points 1 week ago* (last edited 1 week ago)

In that case, I suppose I should wire it in series with the “new” (harvested) thermostat that will be the replacement. Then both the t-stat and the mystery component would be able to open the circuit.

I suppose I could test it.. if I warm up the plate with a heat gun, I could see if the mystery component acts like a thermal breaker.