I keep reading your question. I am unsure what you are asking or why. But I will provide this for an RV absorption fridge.
If the fridge compartment is at 30F and you turn the fridge on, not much will happen as the temp sensor in the fridge compartment is already at or below the setpoint. And as was stated, the freezer will not get any colder either, as it only adds a cooling effect when the fridge compartment calls for cooling. There is no separate control for the freezer; it just comes along for the ride, so to speak, when the fridge compartment requires cooling.
You can try this, it should work. Take an empty milk jug, fill it with warm water from the house, place it in the fridge compartment, and close the door with the fridge on. The heat energy in the jug will start warming the fridge compartment, and in time, the fridge will begin cooling. In your case, the fridge needs a heat load "inside it" to operate.
Also, be careful as if you want to go run the system at much colder temps, you need to deal with that situation. Some block off a portion of the lower outside vent and put an incandescent light bulb warming in the outside cabinet where the cooling coil is, or look for a cold weather kit. Research this out for your brand fridge, assuming you use an absorption fridge.
Hope this helps
John
2005 Ford F350 Super Duty, 4x4; 6.8L V10 with 4.10 RA, 21,000 GCWR, 11,000 GVWR, upgraded 2 1/2" Towbeast Receiver. Hitched with a 1,700# Reese HP WD, HP Dual Cam to a 2004 Sunline Solaris T310R travel trailer.
