I just changed the ADC in my fridge because it was running warm. Today I see ice on the back panel in the freezer section and the fridge is warm again. HELP??

What is the ADC and why did you change it? We need to know which model of Maytag refrigerator that you have and if it's a side-by-side or top or bottom freezer, plus about how old it is. Also, are the coils clean? If not, clean them with soap and water by unplugging unit and removing front kick plate and rear panel. Then spray coils down with spray cleaner and wash off with sprayer on water hose with small amount of water and vacuum up with wet-vac. Let refrigerator stay off an hour or two in case compressor has overheated. If freezer is iced up defrost it by opening door. You should pull out condensate pan from front if it's located there and clean it, too. After this is done you will be ready for next steps.

How do I check with a meter?

How do I check with a meter? ANd where are the coils?

The answer to your first question is: https://dl.dropbox.com/u/8010163/Whirlpool%204322537A%20How%20to%20use%20Test%20Equ ipment%20Service%20Manual.pdf
There are two sets of coils: the evaporator coils in the freezer where Freon-134a evaporates and absorbs latent heat and sensible heat, and the condenser coils under the newer refrigerators where heat is lost to the air. If the coils under the refrigerator are dirty the compressor will burn up and ruin the refrigerator. These must be cleaned with spray soap and water like a spray nozzle on a water hose. Vacuum up water with wet-vac; it does not take much water, but it's the only way to clean the coils right. You also want to clean the fan blades. After you get the coils clean under the refrigerator you need to find the defrost timer which can be either under the refrigerator or by the thermostat. It is a mostly rectangular plastic box with wires out one side and a one-way plastic screw on the front. You plug in the refrigerator and turn this until it clicks and turns off the freezer fan and the compressor. When it does this check to see if it is defrosting by looking in freezer. You will hear the heater sizzling a little and a fog will come out of the vents in freezer. If nothing is happening wait and see if the refrigerator comes back on after 15-20 minutes. If it does not then this timer is bad and you will need to replace it. If it comes back on, unplug the refrigerator and totally defrost the freezer for a few hours, or put a pan of hot water in it to speed it up some. It will take a while because ALL of the ice must be melted. Then remove the cover to the freezer coils and you will see the defrost heater with a wire out each end. On a side-by-side it's at the bottom and in a top-freezer or bottom freezer model the heater is wrapped around the coils. Test that with an ohm meter and you should have about 300 ohms or so. If you read infinity, it's bad. The terminator is attached to the heater and wired in series with it. Many times you can just look at the defrost heater and see it burned in two. On side-by-side models the heater is in a glass tube and you can see it burned and sometimes the glass will even be broken. Replacing these parts will give you a new defrost system. Here are the manuals you will need: https://dl.dropbox.com/u/8010163/Maytag%20Refrigerators.zip