I'm no refrigeration engineer. I'm actually an electrical engineer by training. But the way my (now-broken) refrigerator works makes no sense to me. The cooling coils for both the refrigerator and the freezer are located behind the back wall of the freezer. The cold air comes into the freezer and then is circulated throughout the refrigerator using a simple fan. That makes a lot of sense.
The part that doesn't make sense is that the coils get so cold, they freeze up. There's a heater located inside the freezer to heat up the coils to prevent freezing. I've read that, in some cases, the heating element gets so hot, you can actually see it glowing. In my case, there was no glow, as the heater simply stopped working, thereby not allowing the coils to "unfreeze."
I haven't invested the time to come up with a better system, but there must be a better way to architect a refrigerator without using a heater. That just seems completely counterintuitive to me.
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Once upon a time, long, long ago, products were designed and manufactured to be functional and reliable for long life and use. Today, quality and reliability have been sacrificed to bring costs down, increase corporate profit, and to increase future sales by designing planned obsolecence, while retail prices are out of sight. My first Frigidaire fridge/freezer purchased in 1960 lasted over 35 years with only 2 noisy freezer fan replacements; my first Matag washer (1960) lasted 33 years with 1 timer & 1 water pump replaced. etc, etc., Ah, for the good old days before going green and household appliance computer automation that is programmed to inefficiency and premature failure ahead of it's time... One cannot buy a cheap repair component anymore -- you have to buy "an assembly" because no-one troubleshoots anymore --- but that is a subject for another post...
My defrost heater worked so well it was flooding the fridge compartment because the regular drainpipe where the water should flow out and evaporate would occassionally freeze shut and backup. I eventually discovered attaching an appropriately sized piece of soda can from heating coil to just inside drainpipe solved the soggy vegetable problem. I later found such a solution on Amazon.com as well fo rmuch more money than my AL can and self-tapping screw. This design flaw continues to sell many fridges.
There is a timer which periodically turns off the compressor and powers up a defrost heater in series with temperature sensing switch which opens at a relatively high temperature (65degF maybe) and closes at a very cold temperature (-40degF maybe). So when the timer applies power to the series heater & temp switch, the heat melts the ice until the switch warms up to the turn off point. Sometime later the defrost timer again activates the compressor plus in-box temperature controls.
The usual failure mode is that the defrost temperature switch does not properly switch on at very cold due to drifting lower temperature switch point (say -50degF). As a result, the heater never turns on to defrost the coils and the moisture builds up until the coils are clogged. To confirm, locate the defrost timer (sometimes on bottom of refrigerator or may be inside somewhere), use a screwdriver to advance the timer into defrost mode, and then short out the defrost temperature sensor (Maybe you do that with the power off) to see if the heater comes on. If so, solution is to replace the defrost temperature switch.
To DW- Ya, up North the compressors get cranky. More so in the new units it seems. My refrigerator/freezer out in the garage quit a couple of winters ago due to the cold. I got a heating tape from the local plumbing supply store, wrapped it around the compressor, and plug it in every fall. The heating tape turns itself on around 40 degrees(F), keeps it all working all winter long.
Try a hand-held hair dryer the next time..... not hot enuf to melt plastic, but more than warm enuf to melt ice, and a heck of a lot more convenient than chugging over pots of hot water for hours on end.
There has been much discussion on the energy use side about the heaters in refrigerators (coil defrost and ice tray) and how much energy that the heaters use versus the more efficient compressors and controls now in modern refrigerators. This will become a greater focus of the save energy forces in the future so expect to see some alternative solutions.
On the consumer side most people today do not have a clue that refrigerators have heaters in the unit.
As for refrigerators in cold environments, most have warnings about this issue in the user manual but, as we all know, who reads a manual.
"Got to have it out of the box NOW, NOW, NOW!!! and plugged up NOW, NOW, NOW!!! and have/make it work NOW, NOW, NOW!!!"
(Many times I have helped family members, coworkers, neighbors with some sort of new appliance or machine set up, assembly, etc problem by my actually referring to the item's included manual in a methodical and calm manner even to the point of exasperating the person who asked for my help.
My attitude is "tough" - if you are too impatient, lack mechanical ability, or lack troubleshooting ability then your feelings are not my problem when you ask me to help with solving something that just following the manual instructions could have avoided.)
Fraid not Al but it surely would have been my pleasure. I live in Oregon now but spent most of my career working in So Calif. Gen Dynamics, Pomona; General Electrodynamics, Pasadena; Lockheed Electronics; Leach Controls; Philco Ford Semiconductor; Odetics and then private law practice.
By any chance did you work with me on a blimp project in the Florida Keys several years ago? Then again maybe there are more than one old EE/lawyer combos around, as strange a combo as that might sound. Looking backward from the present my life has been nothing short of wonderous and filled with wonderful and interesting (for the most part) people. No way can I ever stop working.
I'd--thankfully--forgotten about manually defrosting the freezer, and tekochip's description brought back the memories. Uh, thanks? At least they remind me to be grateful for modern self-defrosting machines.
For industrial control applications, or even a simple assembly line, that machine can go almost 24/7 without a break. But what happens when the task is a little more complex? That’s where the “smart” machine would come in. The smart machine is one that has some simple (or complex in some cases) processing capability to be able to adapt to changing conditions. Such machines are suited for a host of applications, including automotive, aerospace, defense, medical, computers and electronics, telecommunications, consumer goods, and so on. This discussion will examine what’s possible with smart machines, and what tradeoffs need to be made to implement such a solution.