I have a 1950's model General Electric refrigerator. It has a little freezer box with a door and the control knob is on this box. This winter it has began defrosting and not kicking on the motor to re-cool. This only happens when it is extremely cold inside my house. Does anyone know how/why the temperature outside the fridge is affecting the thermostat?

Possibly it needs repaired as the thermostat sounds like something's not right. That's almost as old as I am! Glad to hear it still works. My mom had one just like that when I was a kid.

Sounds like defrost timer moter has finally died. Don't why outside temperature would affect it unless there is moisture getting to timer. How cold is extremily cold. How do you get fridge started again.

I sometimes leave home for a week at a time, I heat with wood, so in the winter it can get to be in the low 40's, sometimes in the 30's. I have replaced the door gasket some time ago, but it isn't exactly air tight. As long as the kitchen air is warmer than the indoor set temp. (which is 33-34 degrees), the motor kicks on and holds it's temp. If not the motor does not come on, freezer box defrosts etc.

Ok, sounds like you really don't have a self defrosting refrigerator. Which also sounds right for a 1950's refrigerator. Didn't think they made them that far back. The cooling unit is the freezer compartment. When the temperature in the refrigerator is 33-34 degrees, the freezer compartment will be about 10 degrees. It's a balancing act, no separate controls. When the temperature outside the refrigerator is at about 30's or 40's the temperature in the refrigerator compartment stays at 33-34 for a longer period. The thermostat in the refrigerator is satisfied and sees no reason to start the compressor. During this longer period however, the freezer compartment is warming up to the 33-34 temperature of the refrigerator compartment. If the temperature outside the refrigerator is 33-34 or below the inside of the refrigerator will never warm up enough to make the compressor come on. Not much you can do unless you can set the refrigerator temperature lower while you are away.

Why isn't the door gasket sealing?