The method of on-site inspection of common faults of freezer is similar to that of refrigerator.
Test: when the freezer fails, a multimeter can be used to measure whether the power voltage is normal.Control circuit, fuse, ac contactor coils and contacts, over-current protection relay, temperature relay, pressure relays and solenoid valve coil, the winding of the motor can use a multimeter for testing.
See: see whether the working pressure indicated by the high and low pressure of the unit is normal;Whether the needle of the pressure gauge oscillates violently, such as oscillating indicating mixed air in the refrigeration system;It is abnormal to see the frosting on the evaporator surface, such as the frosting on the evaporator surface is not satisfactory, frosting on the evaporator surface, alternating frosting on the surface, or frosting on the suction end of the compressor, shell or cylinder cover.See if there is frost or dew at the inlet of the dry filter, solenoid valve and thermal expansion valve.See if there is any oil mark on the shaft seal and the connecting parts.See whether the oil level in the crankcase of the compressor is normal;See if there is too much dust on the condenser surface. If there is too much dust, it should be cleaned timely.
Listen: when the compressor is in normal operation, it makes a uniform and slight "cobbler" sound, and the valve plate is a slightly uniform "drip, drip" sound.The "clang" sound in the compressor crankcase is caused by the excessive clearance between the crankshaft and the connecting rod.When the compressor is running, there is a "through, through" percussion sound in the cylinder, indicating that there is a phenomenon of liquid strike, oil strike, or suction valve components have fallen into the cylinder;The "squeak, squeak" of heavy friction in the compressor is generally caused by dry friction caused by insufficient lubricating oil.The sound of clattering and clacking in the compressor indicates that metal parts inside the compressor collide.The belt makes a beep or beep sound, indicating that the belt is slippery or damaged.The intermittent "hissing and hissing" flow in the thermal expansion valve indicates that the cooling dose is low or there is ice blocking.
Touch: when the unit stops running, turn the compressor V belt wheel by hand, which should be able to rotate flexibly.After 1h operation of the unit, touch the temperature of the suction and exhaust pipe of the compressor by hand. The exhaust pipe should feel hot.Dip your finger into the water and touch the evaporator for a good suction pipe.Touch the compressor cylinder cover, high pressure side heat, low pressure side cool, if there is no temperature difference, it indicates that the compressor cylinder cover asbestos rubber gasket broke, high pressure cavity gas.Touch the temperature of the bearing cover before and after the compressor is generally not more than 70 ℃, if very hot or just slight fever show that system is not normal.