Use a multimeter to check the DC resistance value of the defrosting time relay motor, it is about 8 kilohms when it is normal. If the resistance value is normal, you can turn on the power for further inspection, listen to the sound of the motor moving, there is a sound indicating that the motor can work. If the defrost timer is damaged, it can be repaired or replaced. If the defrost timer works normally, check the defrost thermostat again. When the ambient temperature is +13℃, the thermostat should be disconnected. If it is on, the thermostat is broken. If it is normal, this thermostat in the freezer of another refrigerator and freeze it at a temperature lower than -5℃ for 10 minutes. It should be turned on when measuring with multimeter R*1. If it is broken, the defrosting circuit is blocked, so it cannot be defrosted. If the defrosting thermostat is damaged, it can be replaced with a new one.
