So I've received an old top freezer fridge for free that I plan to use for fermentation. I had hoped to be able to maintain freezing temps in the freezer while fermenting in the bottom by hacking the controls for it. I've got it all torn apart and discovered the control system for blowing cold air into the fridge section is entirely passive. A knob labeled "freezer temp" manually closes and opens a damper for cold air into the freezer. Warm air return to the evaporator in the freezer is just open. "Fridge temp" controls the relay to turn the compressor and evaporator fan on/off based on a temp sensor in the fridge.
This all seems pretty squirrely to me, but my conclusion is that I can:
A. Turn the freezer control to "coldest" (close the cold air damper into the fridge), control the fridge power with a Ranco or similar, and hope for the best.
B. Get real fancy and control the freezer with one controller, then use a PID controller to control a servo motor hacked on to the damper control while also sealing up the damper (it currently still allows air even all the way closed).
Anyone have any other ideas?
This all seems pretty squirrely to me, but my conclusion is that I can:
A. Turn the freezer control to "coldest" (close the cold air damper into the fridge), control the fridge power with a Ranco or similar, and hope for the best.
B. Get real fancy and control the freezer with one controller, then use a PID controller to control a servo motor hacked on to the damper control while also sealing up the damper (it currently still allows air even all the way closed).
Anyone have any other ideas?