Boy I'm glad I found this thread. I too have a Maytag MZD2766. I was initially blaming the kids for leaving the door ajar because it was intermittent at first. Then I noticed after a week or so I would have to manually defrost the coils because the ice/frost was preventing airfow into the refrig compartment.I could use it if nobody else responds...
I did the little test of shorting L1 and Test on the ADC and sure thing I got a buzzing sound. After a trip to the parts store and $60 later I installed the new ADC and preformed the L1 - Test short. The compressor turned off and the the heating coil came on. Bingo. Bad ADC. I saved $100 bucks, learned about the defrost cycle, and apologized to the kids.
Thanks a million
Oh if anyone wants a bad ADC let me know and I'll send it to you.