Hello Jesus, without quackery, first disconnect the refrigerator from the power line and use a domestic fan, place it as close as possible to the entrance of the frezzer at the top. All this is to speed up the rapid defrosting of the accumulated frost, keep the fan for 6 or 8 hours, depending on the ambient temperature, if there is more cold weather and if there is less heat. After this process has passed, you must remove the cover or tray of the frezzer that conceals the evaporator coil and locate the hole of the drain conduit, which should be just below the evaporator, through this conduit you should try to pass a tape or cable , with the strength and flexibility, necessary at the same time as allowing it to be introduced through the entire drainage duct from the inside to the outside of the belt, to ensure proper cleaning, adding plenty of water to drag with it all particles of dirt, that may have been obstructing the drainage system. Once this first part is completed, you must measure the defrosting resistance with a multimeter, on the smallest scale of ohms or diodes, it cannot show a value of 0 or an infinite value, as it would be obviously damaged. Then you must measure the thermal fuse that is connected in series with the defrost resistance, this must have continuity with an approximate value of 0 ohms, when measuring it with the multimeter. The defrosting timer must be held in the hand, to perceive its vibration when operating its engine, we can also see its operation, if it is made of transparent acrylic or models that have a rear viewfinder, you can also make a mark on the rotary knob of the timer itself, which helps us to manually set or remove, at the same timer, the defrosting process and see if as time goes by said knob when moving, changes its initial position, thus demonstrating that it works, supposedly well said timer. The bi-metal to check it, the correct thing is to wait for the refrigerator to start and work for about 5 hours, enough time for the compressor to bring the equipment to an optimum temperature level, and then perform its test. At that time, the Timer's rotating test knob must be manipulated and brought to the defrosting position, turning it clockwise in favor of the hands of a clock. After the defrosting process has started, we place an amperemeter clamp on one of the phase power input cables to the equipment and take with a clock, the working time of the resistance and the bimetal, guided, through the reading that begins to provide the ammeter, that for an amperage of resistance consumption, between 1 and 2 amperes, the activated bimetal must keep said resistance running for more than 15 minutes. If the bimetal fails to be active for that period of time, it would obviously be damaged and could well be the cause of the current problem presented by your refrigerator, if the bimetal, manages to exceed those minutes, for example getting to keep the resistance active, until about 20 minutes, it would indicate that said bimetal is perfect. All the above mentioned data in case of not being correct including the cleaning of the drainage system of your refrigerator. All repeat, failing that would cause the same symptom and therefore the same accumulation of excess frost in the evaporator and block both the ventilation ducts and the evaporator itself in the part of the frezzer and cause the immediate lack of cold in your team. Good luck with the company. S @ lu2 friovega63