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Freezer fridge defrosts when operated in a cold room

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james_s:
I've had this same problem with the fridge at our cabin, if there's a cold snap and I've left ice cream in the freezer it melts. I've temporarily solved the problem by placing an incandescent nightlight inside the fridge on an extension cord over the coldest season but this is not totally ideal. I've been meaning to build a circuit to turn on the fridge light if the freezer gets too warm.

Peabody:
One of these:

https://www.adafruit.com/product/1782

along with an Arduino, a relay, and a wall wart.  The relay could be one of these:

https://www.digikey.com/en/products/detail/omron-automation-and-safety/G3MC-202P-DC5/1789941

Siwastaja:
Just get a proper dual compressor fridge/freezer, or even better, separate fridge and freezer. Installing heater to a fridge to let the flawed design "work" in an environment where it's not designed to work sounds like a horrible waste of energy.

Used freezers go in second hand internet services whatever you have there for a few dozen bucks.

james_s:
The heater in this case need only produce a trivial amount of heat, it's more efficient than heating the room and it prevents the fridge from getting too cold and freezing things even if it's below freezing in the room. I don't know about the OP's case but in mine, the cabin is like a time capsule with all the original vintage appliances installed in 1973 so replacing the fridge is not something I'd want to do. It's true that a modern fridge would consume less power but the fridge is the only thing we leave on when nobody is there and the power it uses is not enough to exceed the base charge for having the electrical service connected.

Peabody:

--- Quote from: james_s on October 17, 2021, 04:21:58 am ---I've had this same problem with the fridge at our cabin, if there's a cold snap and I've left ice cream in the freezer it melts. I've temporarily solved the problem by placing an incandescent nightlight inside the fridge on an extension cord over the coldest season but this is not totally ideal. I've been meaning to build a circuit to turn on the fridge light if the freezer gets too warm.

--- End quote ---

Have you given any thought about how the circuit should work?  As I understand it, the "garage kit" offered by manufacturers supplies heat all the time.  That's no good.

It might be as simple as having the nightlight controlled by the added freezer thermostat.  But I'm not sure if there would be hysteresis issues.  And should the amount of heat generated vary with the ambient temperature?  What about defrost cycles?

It would be nice if we had the definitive, most efficient, circuit for the EEVblog garage kit, requiring no modifications to the fridge.  And of course, costing no more than $25.

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