There are two things that determine how fast a refrigerator gets cold.
- How powerful the refrigeration unit is in BTU per time
- How fast heat is lost through the side and door insulation in BTU/time. The better and thicker the insulation the lower the BTU loss/time.car electric refrigerator Manufacturers
Now the BTU of heat removed can be Rate of input refrigeration BTU/time minus insulation heat loss BTU/time. If the number is positive it will cool down and the mor positive it is, the faster it will cool. Presuming the system has a thermostat it will shut off the refrigeration and not overcool.
But the speed depends on those factors I mentioned.