How to rectify refrigerator from over freezing

The following may be the reasons. You check one by one and see what will be the cause. But I feel it is better to call a mechanic who will check and do the needful.
The following are the most possible reasons.
1. The Thermostat might have been set too high. The knob of the thermostat might have been fixed at a very low temperature which will cause the compressor to work a long time and consequently ice formation will be too high. It is better you check the knob once and adjust it properly. Automatically the freezing will come down.
2. There will be coils present in your refrigerator. These coils will be there inside the refrigerator as well as outside also. These coils are heat exchanging medium between the refrigerant fluid and its surroundings. If they are getting dirty and not cleaned properly, freezing will increase.
3. There will be a Gasket line inside the refrigerator door. It will seal the compartment to prevent the exchange of heat. If the gasket is leaking, the refrigerator will run continuously.
4. The fridge will have a thermostat and we can fix the temperature at which this thermostat will cut off the power supply and the cooling effect will not be high or the other way round. If this thermostat is not working properly and there is no cut off aking place you will have this problem.
5. If the damper is not functioning also it will lead to overcooling and freezing.
By seeing these points and setting them properly will make the problem come down.

In old type of fridges one has to manually defrost the fridge by pressing a button or switch to off the power to the circuit compressing the refrigerant in the cooling tubes in the freezer compartment. This action would start melting the thick layer of ice which had been formed in the freezer compartment. The water collected in the tray below the freezer compartment is then to be manually thrown out of the fridge. Once the defrosting is complete the new cycle begins. To get minimum ice to be deposited in the freezer compartment it is essential that the thermostat should be properly set so that the ice should not be formed much. In the new model fridges the defrosting mechanism is automatic and whenever ice is formed the defrosting thermostat would disconnect the electric circuit powering the compressor sending the compressed refrigerant to the cooling tubes around which the ice starts to deposit. If the setting is correct the ice would not accumulate and melt before that situation. There is one subtle point to it that sometimes there might be some leakage in the sealing gasket of the freezer door and some air might continuously leak out and so the thermostat might not switch off or switch on at that crucial setting. This might bring a mismatch in the melting of the ice. Due to the small entry of warm air from outside to freezer compartment the frosting would happen and ice would start depositing in the floor and sides of the freezer chamber and slowly that would go on accumulating to become a thick sheet everywhere and would further effect the setting of the thermostat as the thick ice sheets change the combined thermal conductivities of the cooling tubes superimposed by ice. This is undesirable and leads to further accumulation of ice.

Another important thing is that if the fridge owner is absent from the house for a long time and fridge is on and naturally the freezer door is not opened then the cumulative ice formation take place in the freezer compartment over a period of 3-4 months. This is a unique and rare problem but is encountered in certain near optimal settings of thermostat. It is advised to clean these cooling tubes (known as evaporator coils) once a while with little vinegar and warm water so that they are in a good shape and conduct heat as desired in the original design. Generally the thermostat settings are kept in such a way that as soon as the freezer temperature goes down to 2-3 degree centigrade the thermostat trips the freezer cooling circuit off.

The refrigerators have to well maintained so that it could a longer shelflife.
The freezer is overloaded with ice and the defreezer does not work means it may be the problem of thermostat. Thermostat is used to control the temperature, it is better to get a technician replace the thermostat fot the proper functioning of your refrigerator.

A thermostat is the brain of the refrigerator that controls the temperature. If your refrigerator is over freezing then there could be a bad thermostatic temperature controller. In such a case, the refrigerator runs continuously. You should get this checked by mechanics, get this replaced.

Another reason is if the coil of the refrigerator is dusty or dirty then the compressor needs to works longer to keep the temperature of the refrigerator at freezing temperature. In this case, the refrigerator starts over freezing. You can clean the coil that may solve your problem.

Sometimes we set the temperature of the refrigerator at too low or warmer, this also creates the problem. You should adjust the temperature on average or as per the weather condition.

The refrigerator's door has a gasket, make sure it is properly sealed. If the gasket is not properly sealed then the refrigerator will run continuously and this can cause the freezer section to get over freeze. You should check this properly if it cracked or worn, get a new gasket and replace it.

Make sure you get this checked with a professional mechanics.

What is the ambient temperature in your place? Is it cooler at night?
If the outside temperature is less, then there is a greater chance of ice formation especially in fridges without auto-defrost or 'no-frost' machines.
Check the temperature control valve/switch in your fridge. Keep it to a lesser cool pointer. (say medium or normal).
It may work. Depending on things kept inside, you may have to arrive at optimum control by trial and error and monitoring and reviewing. Sometimes you may need to reduce cooling in the night and increase in a day.

When you keep things inside the freezing cabinet, dry their outside free of water droplets.
Do not keep things that are prone to 'sweating' or emitting water vapour. Do not keep the fridge open for more allowing the humidity to enter the freezer cabinet. There may be some leak of water vapour from lower cabinets entering into the freezer cabinet which gets froze. To avoid this ensure the freezer inside cover is properly fitting and closing without leakage. Sometimes small ice blocks at corners may prevent the inside partition door/cover from closing tight.

Next time defrost by putting off the fridge and disconnecting from the power point. When the iceblocks start melting, carefully remove those blocks manually. Ensure that there are no residual water or ice slabs left at hidden places above or sides of the freezer cabinet. Be careful not to break thin wires or probe or bulbs inside. Wipe sides fully dry with dry clothes. Then ensuring that it is fully defrosted, switch on the fridge again. Keep the cooling control at normal or moderate. If there are no easily perishable things needing high cooling you need only moderate or normal cooling.

If again the issue persists, contact a technician.

The freezing container full of ice can be due to the defrosting is not done by you in routine. The full freezer container is generally on rainy days as there is moisture in the air and the same freezes in the freezer.

You must do de-frosting in every two days. Or switch off the refrigerator for a few hours until the ice melt.

Keep the thermostat to the desired temperature level.

Also, never keep refrigerator door open and check the magnetic door closer working.

If above solutions do not solve the problem; then it seems the thermostat is not working or there is a gas problem in the refrigerator. So, contact the mechanic to sort the issue.