"Brian Gaff (Sofa)" wrote in message
...
Well as you know, I have opposite problem as its the fridge that does not
defrost, but my fridge definitely does not have drain anywhere, and it
kind of makes one wonder how it was supposed to work. The defrost works it
just comes out the door at times when its opened.
In the case of the original query, does the freezer actually look coated
in ice? From your description it sounds like its only in the pipe. In that
case perhaps the pipe is supposed to be insulated from the cold and the
insulation has gone and hence its freezing up. Normally you would expect
freezer insulation to prevent this problem as the air is supposedly warmed
as it exisxits with its water vapour by going near the hot end of the heat
pump.

How does auto-defrost of a fridge or freezer work? Does it run the
compressor "in reverse" (or use a heating element near the heat exchanger
inside the fridge/freezer cabinet) to make the accumulated ice melt?

I ask because we've recently started monitoring the power consumption of our
freezers minute-by-minute (*), using TPLink HS110 remote
controlled/monitored sockets, and we've noticed that every day or so the
power consumption increases from a normal 30-60 W to about 200 W for maybe
10 minutes, in amongst the normal 20 minutes on / 40 minutes off cycle. This
suggests that a) the compressor motor has current control, in addition to
simple off/on of a thermostat, and b) that something is triggering it into
the higher power state occasionally.

What typically fails when a freezer maintains a constant temperature and
looks to have no ice on the heat exchanger, but then suddenly ices up and
starts to warm up, needing manual de-icing with pans of warm water before it
will get down to -18 again? That's happened several times over the last year
with another freezer (kept indoors) and it's unlikely that on every occasion
we might have left the door slightly ajar. It's as if the frost-free
mechanism works perfectly most of the time but occasionally fails.



(*) Partly to watch for equipment failu we had a freezer outside in the
garage (yes, a Beko, rated down to -15 deg C ambient temperature) and the
other day I noticed that the food was a bit soft so it had failed sometime
in the last day. There followed a day of frantically cooking all the joints
of meat that my wife had bought when they are only on sale at Christmas, for
us to eat throughout the year, and then we re-froze them. The freezer seems
to be completely dead: the last junction point before the motor is getting
power, and any thermostat is beyond that point in the sealed motor unit.