Or just replace the relay with a switch. Must of these automatic
defrosting fridges defrost so often that they freezer-burn and ruin
your food.
It's hard to tell whether it's 'defrosting' an element that is in any
case more or less ice free. The element isn't visible without detaching
the backplate of the freezer, and running the fridge without the
backplate in place would so change the airflow as to make any
observations irrelevant to the normal operation of the fridge.
The reason I got started on this whole exercise was the fact that at
times the bread in the fridge was clearly not frozen, even though the
freezer temperature certainly drops to less than -15C at times. I hadn't
previously looked into the defrost mechanism, and indeed, didn't realise
that there is actually a quite powerful heater element involved. Nor did
I realise that the defrosting occurs every six hours.
A particular issue with the defrost mechanism is that it has a defrost
termination thermostat mounted on the cooling element (set to open at
+11 degrees celsius, closes again at 0C), but regardless of what it
does, the fridge remains in its non-cooling mode for about half an hour
because of the defrost timer. I put a temperature sensor onto the
thermostat, and it shows that the actual temperature there rises to
nearly 20C, presumably because even after the heater is turned off, it's
still very hot.
In addition, there's no link between the defrost timing and the
thermostat. Defrosting may start just as fridge has reached its highest
normal temperature and the termostat is about to turn the compressor on.
So the day to day outcome will vary considerably, even ignoring ambient
temperature changes, making assessing whether the thing is working
properly rather problematic.
Now the bread is probably the thing in the freezer that has the least
thermal inertia. Maybe the fridge has been working correctly (in the
sense of "as designed") all along, and I've just been overreacting to
the occasional thawing of the bread.
I've now learnt stuff about self defrosting fridges that I might have
been happier not knowing.
Sylvia.