Maybe it could be combined with thermostats? E.g. one for "if it ever gets hotter than N degrees, disconnect all heating elements and trigger some alarm", another one for "if it's warmer than X for longer than Y minutes, do the same". That could also be to the network, too, it just would never read from it, or from anything electronically. Just bimetals closing or opening circuits, basically. How expensive would that even be? (If you planned for it from day 1 of the design I mean, not retrofitting things)

> Maybe it could be combined with thermostats? E.g. one for "if it ever gets hotter than N degrees, disconnect all heating elements and trigger some alarm", another one for "if it's warmer than X for longer than Y minutes, do the same".

Why would they alarm when they were instructed to initiate a defrost cycle and heat up?

(Most medical-class freezers to have an alert function that sends an e-mail, SNMP trap, etc, when things go "wrong", but defrosting 'as requested' is hardy "going wrong".)

Or just do it the better, manual, way - point a heat lamp and fan at it with the unit open. Even if you melt the ice inside, you still need to remove the moisture. The manual process is not that intensive and needs to be performed very infrequently.

Fridge at home totally, no idea about blood banks, but freezers in supermarkets probably not so much? I would imagine being able to start a warming cycle, then going around with dry towels to wipe out the water, especially if you have to do it while the store is open, is a lot more feasible.

But how about this, maybe something that keeps an eye on the state and rate of ice buildup, and helps schedule doing it when it's actually necessary, and maybe helps spot issues that cause quicker buildup.

Yeah, even at home towels are used.

That could be useful. An easy implementation might to to track temperature trends with power draw relative to the other units. You might have to account for door openings, but seems like a good way to mark units for mechanical inspection.