On an old fridge or freezer, the bigger number and thicker part of the line typically indicate colder temperatures. This is because older refrigerators and freezers often use a manual temperature control system, where a dial or knob is used to adjust the temperature.
In such systems, the temperature control dial or knob usually has a scale or markings indicating temperature settings. The scale might range from 1 to 5 or 1 to 10, for example. In this case, a higher number on the scale, which corresponds to a thicker part of the line, typically represents a colder temperature setting.
By turning the dial or knob to a higher number, you are increasing the cooling effect, which results in lower temperatures inside the fridge or freezer. Conversely, turning the dial or knob to a lower number would reduce the cooling effect and result in higher temperatures.
It's important to note that this may not apply to all refrigerators or freezers, especially more modern models that utilize digital temperature controls or have different temperature scale designs. Therefore, it's always advisable to refer to the specific appliance's user manual for accurate information on temperature control settings.