The temperature control knob on the fridge is what you use to control the thermostat and set the desired temperature for your fridge and freezer. Based on the temperature you've set, the temperature sensor or thermostat will turn on the compressor at certain intervals to ensure the desired temperature is maintained.
However, in case the control knob is broken, you could be looking at a number of possibilities. Some problems will only call for a simple correction while others will require the intervention of an expert in repairing refrigerators.
Possibility One: Only the Control Knob is Broken
This is the best case scenario and this is when the control knob might have suffered some sort of physical damage. The knob may be broken or unable to turn properly. However, since it's only the knob that's broken and not any of the systems it controls, you will still hear the fridge cycling on and off at regular intervals.
For people who rarely adjust their temperature settings in the fridge, this might even go unnoticed for a long time. This is because the fridge will still be performing its normal functions based on the temperatures previously set. However, it will still be advisable to change the broken knob for later.
Possibility Two: The Temperature Sensor or Thermostat is Broken
If there is a problem with the temperature sensor or thermostat, it may not be possible to continue using your fridge without repairs. In such a case, you could have a compressor that never cycles on or you could have one that is always running.
Therefore, your fridge will either not be getting hot enough or, it will be getting so cold that it freezes everything including items in the fridge. If the compressor is always on, the sensor may not be completely broken but still defective.
This problem is hard to ignore and the remedy requires that the damaged part be replaced as soon as possible. If your fridge is always on, you could also incur high energy costs.
Why You Need to Work with a Professional
When you need to replace something like a temperature sensor in a fridge, you will need to know where it's located, you'll need the right tools to do the job and you'll also be dealing with a lot of electrical stuff. In such a situation, rather than take a chance and make a serious mistake, it's better to bring in an expert.