[jmac]

during defrost cycles, fridge makes a very load pop sound, (like a small firecracker).\
It is probably either sheet metal or plastic parts expanding and contracting as the fridge goes thru the defrost cycle. I am unable to pinpoint the exact location of the sound as it does not occcur every time and when it does it is so loud that you have a problem pinpointing the spot it came from..
But it is very annoying, especially in a quiet house.
Has any one experienced this problem with an Maytag fridge?
Where do I look to find the problem and how do I access the area to fix it?

[woodchuck]

In this diagram you can see your heater, evaporator coils and heater shield. Parts 9,14 and, 10. They're all behind the cover #2. Any parts close to the heater could cause noise when hot and water dripping on it. The shield should be positioned so the water doesn't drip on the heater.
Maytag MTB2156BEW Parts List