We had a few instances that it seemed like the freezer was getting to warm. It was pointing toward the defrost thermister, which is part of the controller board. . Also – when boondocking, I’d like to disable the auto defrost mode. Why burn through amps to defrost when I really don’t need to.
I checked the price of a controller board, $100. OUCH. Yah, not going to happen. I decided to make my own controller and add a few features . I did all the preliminary testing and designed a board to replace the original. It would behave like the original, but have a few features and displays that the original doesn’t have.
Based on an ESP32 microprocessor, I drew the diagram and created a new circuit card to replace to old one.
The controller is programmed and operational in the refrigerator. The Operator panel has been updated to support the control module.
Features includ
The controller has 5 preset set points.( 44, 42, 41, 39, 38) The set points number (1 – 5) are displayed on the normal refrigerator control panel. Set points can be changed at the refrigerator, just like the original, OR, they can be changed on the Control panel. Another feature, when SP5 is selected, the compressor is actually controlled by two set points, the food (38) and the freezer (15). If the food goes above 38 or the freezer goes above 15, the compressor runs.
Normally the Defrost cycle happens every X hours of compressor running. I wanted to be able to disable this when we boondock to eliminate the current draw from the batteries.
From the Operator screen, the Automatic Defroster can be disabled. The defrost mode can also be forced to start / stop.
The control board has 5 LEDs to show what set point is selected. If the wifi connection goes down, the four set point LEDs that are not selected will blink to show no wifi connection.
If wifi goes down, the controller continues to function in its last mode.