I got a call last week of a "tapping" in the frig. It's a Whirlpool bottom mount. I open the freezer door and I knew it was the evap fan. I pull the freezer door off, by the way, when you push in the clips n the slide rails to remove the door all in one piece, standing against the wall the door just makes it over the top of your feet. I only mention this because I'm 6' 4" and 300 LBS. and to get behing the frig you have to literally move the washing machine laying against it completely out of the way.
After I remove the freezer door I see 1/4" solid ice on the freezer floor, remove the evap panel that was fun laying on the floor in front of this, and there is a slight build up of ice around the fan, that's what was making that "tapping". No ice buildup on the evap and the drain was absoutely clear. I know the heater works or else I wouldn't have the ice one the inside floor. I order the controller and another evap motor, I don't trust these 12 vdc motors if they been banged around. So I can do the job right.
I go back yesterday for a "30 minute" job total, I thought. I take it apart again and install the controller. After I plug it in I always wire tie these back into the same position on the side of the evap where I took the original two sensors from. Swap the evap motor and I replaced the thermistor. Plugged in the fans and NOTHING!!! And I laid there 25 minutes rechecking everything and the fans would not come on. I even taped in the light switch just in case. no difference.
I pull the main board cover, after I moved the washer, and pushed in the test button on the board and everything came on, including the fan. I took my resistance reading on the frig and freezer thermistors, the readings matched the temps.
THE MAIN BOARD"S BAD. My customers were not happy, they had a PA., nor was I. When I was putting the thermistor though the opening in the panel I decided to put the old one back in. As soon as I unplugged it the fans came on. Plug it back in and they turned off. Tried this with the other one one, the same exact thing!
Just one of those days, when I went there originally and told them I was going to replace the evap fan, they wanted a new frig, you can imagine what they want now. I'll find out if I was right when I replace the board next week.