This is a 15 yr old Kenmore (GE) refrigerator with top mounted freezer...
I knew, for awhile, that I had a DEFROST problem. That was causing water to collect on the inside bottom of the fridge, under the veg./fruit bins. And then occasionally run out onto the kitchen floor if I didn't sop up the water inside. But I delayed the repair because of the hassle of emptying the food, top and bottom, and finding temporary homes for it all. Until I noticed 3 things happen in short order.
1)The water stopped leaking out. (2)The ice maker suddenly quit working. (3)The refrigerator portion was no longer cold enough. (Also found the back wall of freezer loaded with frost.)
Newb to fridge repair, but watched enough videos to kinda-sorta 'know' what I had to do.
Symptoms said either defrost timer, defrost thermostat, or defrost heater...or some combination of those parts, were bad.
So first I emptied the unit, then found the defrost timer (was in the fridge section between the damper control and fridge temp. control. Advanced the timer manually to start the defrost cycle.(When the fans stop and compressor stops, you know that's the spot!) Then I waited, watching the clock.....45 min. later, the fans and compressor started up, so I knew the timer was not the problem. (Nor the fans or compressor!)
Unplugged unit. Unplugged the ice maker. Removed it, the light and it's cover, and the air vent grille from the freezer section. Unscrewed the one screw holding the back panel of the freezer in place.
As I assumed, the evap coils and surrounding area were covered in ice/frost.
Used a hair blower on HIGH for 10-15 min. to remove it all and dry things off.
I could immediately see the thermostat was bulging out of shape, so I knew it was bad.
Immediately came here and ordered a new one. (Using the cheapest STANDARD shipping option the part came in LESS THAN 24 HOURS!!! AMAZING!!)
Since all was defrosted, while waiting for my new thermostat, I tested the drain line by dumping a small cup of water over the evap. coils.....Water gushed into the fresh food compartment, so I knew I also had a plugged drain line.
Luckily, that line sticks out the back of the fridge and was easily removed. Sure enough, I flushed out a charred piece of styrofoam insulation from the freezer, which had worked its way into the line, eventually (with other gunk) blocking the water from its normal path to the evaporation pan.
Snipped the two wires to the bad thermostat to remove it. Spliced in the new thermostat using two waterproof silicone sealant filled wire nuts to connect it to the existing wire ends.
At this point, all I wasn't sure about was the defrost heater. I could've plugged the unit back in and waited for the fridge to cycle to defrost mode, but I got impatient. So I ran out and bought a basic digital multi-meter and tested the heater coil for resistance/continuity. It checked out fine.
Buttoned everything back up except for the back panel in the freezer and started the fridge.
It went through a normal run/defrost cycle so I knew I was done. Reconnected all the freezer components. Ice maker started working normally again. I was DONE.
A huge THANKS, to AppliancePartsPros, for the tips and the incredibly FAST delivery!