A refrigerator is a big expense and one you want to research carefully. It is possible to get good deals on brand new fridges, but many small problems with an old fridge can be looked after without throwing out the old to replace it with a new one. Then again, there are some issues no amount of tweaking will overcome.
How old is your refrigerator? If it is more than a decade old, it is probably highly inefficient. Even the efficient models of a decade ago have been outclassed by the latest styles, so think about this: every hour you use your old electricity guzzler, it is costing you money. Keep an eye on your energy bills too. If they seem to be going up, it could be a problem with your refrigerator that is responsible.
It is advisable to place a thermostat in your refrigerator when it gets a bit older, just to keep an eye on how well it maintains the temperature you want. It becomes a problem when you set the machine for a particular temperature and it fails to reach this. Food safety is a major issue here, since perishables have to be kept to a particular maximum. On the other hand, a fridge that gets too cold will ruin your food.
Some refrigerators collect water in the bottom. They leak liquid every few days or after a week or so. You might find this happens more often if the fridge is empty, or it might be a random occurrence.
Sometimes the problem is simple. Pull your refrigerator back from the wall slightly to allow it some ventilation space. Clean out the back of the machine regularly. Dust builds up there, making it overheat. Keep cook books off of the top for the same reason. Consider keeping more food in the refrigerator at one time, or even jugs of water. On the other hand, do not overfill the refrigerator either. Also, clean your refrigerator on the inside regularly.
When Nothing Works
If you have tried all of the solutions noted above and think you will have to call out an appliance repair technician, think about cost. You will be billed per hour or any portion thereof, so you could end up spending almost as much on repairs as it would cost to get a new model.
Then again, make sure your refrigerator is not still under warranty. A relatively new machine should give you another few years of service before you have to think about trading it in.