Ahh, the good ol’ days when refrigerator defrost cycles were controlled by simple mechanical defrost timers. Yeah, used to be a man could go out on a refrigerator service call and make an easy $150 replacing a silly little $25 timer. The old mechanical timers would simply click the fridge into defrost mode every six or eight hours and fire up the evaporator defrost heaters for 21 minutes or so whether it needed it or not. But life never stays simple, does it? Alas, those days are rapidly disappearing.
Instead, the manufacturers have starting using the fancy-schmancy electronic timer boards so they could add an "adaptive defrost" feature. Supposedly, adaptive defrost makes the fridge more energy efficient by making the defrost cycle contingent on the number of door openings and other factors. I think it’s just an excuse to sell more expensive electronic parts that don’t really perform as advertised. It’s probably driven by some gubmint bureaucratic program–you know, the same geniuses who gave us the load of crap about how we can’t use R-12 anymore because it hurts the ozone layer.
Well, no use whining about it ’cause adaptive defrost is the wave of the future, for better or worse. And if you have a newer, high-end fridge, chances are that it has adaptive defrost. And one day, at the worst possible time, it will break.
The adaptive defrost board on Maytag fridges looks like this. To put this board into defrost, short "L1" and "Test" with a small screwdriver and wait three seconds. You should hear a clicking noise from the relay and the fridge will shut off and go through a defrost cycle.
The adaptive defrost on Amana fridges is a little different. A test procedure for this board is shown here. To initiate the defrost cycle, press refrigerator light switch five times in six seconds. If you press it five more times within six seconds, this will cancel defrost and take the fridge straight into run mode. The operation is similar on both the bottom mount and side-by-side fridges. After the defrost terminator/thermostat opens, there will be a six minute delay before the compressor and condenser fan motor start running again, and a 10 minutes delay before the evaporator fan motor starts running. This is important to know because you can really start chasing your tail when things don’t start running when you think they should.
Whirlpool also has some adaptive defrost boards out there. I don’t need to post the diagnostic info on them here because it’s all in the mini-manual that comes with your fridge, usually folded up into a little itty-bitty square and tucked into a slot on the backside of the condenser grill, in front of the fridge.
Ok, so let’s say you’ve determined that your adaptive defrost board is fried. Well, you’ll need to replace that bad boy. Come git you one: