I thought I would write a post after spending days, hours, hands on with the unit and reading online of everyone else problems.
Basically the unit I was working on the freezer just would not get cold enough.
Did some reading.
First thought was the Thermistor. By pulling the connector off the control board you can measure the resistance of each of the 4, pins 1-2 and 3-4 (You have to remove them from the board to measure. leaving them connected to the board adds the boards circuits to the reading). I measured them warm and cold, they all should be pretty close to each other 1.9k ohms warm. Cold is a bit tricky for the two in each compartment measure different temps. One the air, the other the cooling fin/plate. The frig 4.7k/7.1k. The freezer 12.9k/20.5k. Yes the resistance goes up as temp goes down. So all the thermistors were good.
Kept reading. Fan in the freezer? looked into where it was and sure enough this fan was not running.
Figure it had failed, did some more searching, found the service manual and parts diagram to try get the fan out. FYI these fans are a standard cooling fan, described as "75mm x 30mm 7530 12V Dual Ball Bearing DC Brushless Cooling Blower Fan AV-F7530MB" $4 on Amazon. The $70 Dometic replacement come with the wire length and connectors to suit, but for $65 you can just splice the new one in.
With the freezer fan in hand, tested it. By golly it works. So I put it back in and chased down the control board, or "Power Board" as Dometic refers to it, was not turning it on. FYI, turning it on for this control is by giving it a ground, 12V+ is always there. Don't ask. I jumped the ground from the heater wires that are in the freezer to the fan and wala, fan runs and after a day the freezer was at 7 degrees.
NOW, why was it not on.
Did some more reading. Owners reporting by using the Test Mode, holding down the SET button while turn the frig on, the fan would turn on, others reported the Door Switch test would always show the Freezer door open. Another owner report that the fan turns off with the door open (the frig doesn't work that way, fan always on).
So is it the switch?
Dometic, I read, told others to replace it. SO I checked it, the switch disconnects when closed. Worked fine, but the board still shows the door open. The guy at
help@snip-the-tip.com who makes a replacement thermistor FYI, suggested there maybe some resistance being place in the switch wires.
Well, by gosh, I find on the wiring diagram, they splice into the wires and run both of the switch wires up to the Ice Maker control board. From what I can figure, they defeat the ice maker from working when the door is open.
Pulling the 4 pin connector from the Ice Maker Board, the Freezer Fan starts running and the Test shows the door closed now.
Is it that $100 Ice Maker Board is bad, defective, a bad match to the Power Board. Who know, I am going to just leave it disconnected for now and put everything back together