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:

Maytag Adaptive Defrost Control Board	Amana Adaptive Control Board for Side-by-Side Models
Amana Adaptive Control Board for Bottom Freezer Models	Whirlpool Defrost Control Board
Whirlpool Defrost Timer Control Board	Whirlpool Defrost Control

This topic comes up a lot in the forum in various ways, some of them pretty bizarre. In my tireless efforts to help my precious grasshoppers achieve ultimate appliance satori, I’ve put together this handy list of common sources of fridge noises.

1. Some of the newer-design compressors produce a higher pitched sound which can be mistaken as being louder.
2. The evaporator fan (the one in the freezer) makes noise while it does it’s job of pushing cold air around the freezer and fresh food compartments. That’s just what happens when you move air around rapidly in a confined space. On some models, this fan can sound louder than on others.
3. If your fridge is on a floor that’s not level or is weak and buckling, this can cause distortions in the cabinet and make buzzing or rattling sounds, especially around the compressor and condensate drip pan.
4. Occasionally, you may hear a sizzling sound from the freezer. This is just part of the defrost process where ice accumulated on the evaporator is melting and dripping on the defrost heaters below. Defrosting: it’s a good thing.
5. When the fridge goes through its defrost cycle and then cools back down to operating temperature, they’s a whole lotta expandin’ and contractin’ goin’ on in there. This can cause all those mass-produced metal and plastic parts that’re smooshed together to move a little bit and you’ll hear popping and crackling. Don’t sweat the load, everything’s fine.
6. Sometimes, you’ll hear a bubbling or gurgling sound, like boiling water, inside the fridge. Relax, it’s just the refrigerant doing it’s job. The refrigerant boils at a much lower temperature than water. So when it boils and goes from a liquid to a vapor, it’s sucking up heat from inside your fridge. So, this all boils down to this: boiling refrigerant = cold fridge.
7. If you hear a dripping sound from underneath the fridge, it’s just condensate water dripping into the drain pan like it’s supposed to. By the way, if you have a problem with your fridge leaking water on the inside and you pull the condensate drip pan from underneath and it’s bone-dry, that’s a sure sign that the condensate drain port inside the fridge is plugged with ice or gookus.
8. Mechanical defrost timers can make noticeable clicking noises when they switch into and out of defrost mode.
9. Icemakers make some of their own noises. The water valve buzzes when it opens to let water into the icemaker mold. You may hear a trickling sound as water flows into the icemaker. And then there’s the periodic and welcome rattling sound as the icemaker dumps ice into the tray.