Refrigerator & freezer became warm.

Unplugged the refrigerator. I took all the food items out of the freezer, took out the ice bin and shelves. Then I unscrewed the back panel and removed it. The freezer coils were frozen over with ice. Then I used a large fan to thaw the ice and cleaned up the water with towels.
I unscrewed the old defrost heater at the bottom of the coil section, removed it and screwed the new defrost heater part in. I ended up using some dikes to cut the wiring midway up . ( I was going to use the new plastic plug that came with the new part, but it wasn't correct ). I spliced the wires together ( the color scheme was the same - pink to pink, blue to blue, etc), capped them , taped them with electrical tape, and I covered them with a corner from a sandwich bag and taped them a bit more to keep moisture out. Then I tucked the wiring up away from the coil section. I also spliced this little cylindrical part into the existing wiring harness and clipped it onto the copper tubing. ( I suspect this is the defrost timer, but I'm not sure ). After I removed the the old cylindrical little part, I noticed the cap was popped out of it. (it looked like it was damaged a bit ). Once I got all wiring tucked away and back in place, I put the back panel back on, plugged it back in. Voila'. Easy as pie. It's been running fine ( about a week now) ever since. I replaced the thermostat sensor first since that was the cheapest part, but it wasn't the problem. So I moved on to the defrost heater and that ended up being the bad part. I repaired my refrigerator for less than $100.00. Thanks PartSelect. You rock!