Faulting and troubleshooting of vapor pressure temperature controllers
(1) Common faults and common faults of the vapor pressure type temperature controller include contact burning or adhesion, failure of the mechanical transmission mechanism and leakage of temperature sensor in the temperature sensing tube. Its detection method is: put the thermostat knob in a stop, use a multimeter to measure the resistance value between the terminals of the incoming and outgoing wires, if the measured resistance value is zero, it indicates that the contact is adhesive; Turn the knob of the thermostat to the refrigeration position, if its resistance value is infinity, it indicates that the contact is oxidized, burned out or the mechanical transmission mechanism is stuck; When the thermostat knob is set to the refrigeration position, if the contact is not connected or the compressor starts and stops at work is abnormal, it indicates that the thermostat is out of order; Put the thermostat in a weak cold position, and the contact is not connected, and the contact in the strong cold position is turned on. Indicates a leak of thermostat.
(2) Troubleshooting
1) When the thermostat contacts are burned out, the surface is oxidized or cannot be turned on after mechanical clamping, or when the arc generated by the contact at the moment of turning on or off makes it melt and stick, the thermostat should be removed and its metal shell should be pried open for repair. If the fault is that the contact is burned out or the oxide layer is too thick, the contact surface can be directly polished with fine sandpaper; When the machinery is stuck, the dirt should be taken out or a small amount of lubricating oil should be added; When the fault is contact adhesion, it can be pried open and smoothed with fine sandpaper.
2) When the temperature in the refrigerator is higher than the predetermined value and does not turn on or is lower than the predetermined value, the temperature range can be adjusted with a screw cutter and the screw can be adjusted. When rotating clockwise. Reduced temperature control range; When rotated counterclockwise, the temperature range expands. When adjusting, it should be noted that the amplitude of adjustment should not be too large, and it is advisable to turn about 0.5 times each time. When the start-stop time of the compressor is too short or too long, the temperature difference adjustment screw should be adjusted. When the screw is turned clockwise, the temperature difference range can be narrowed; When rotated counterclockwise, the range of temperature differences can be expanded. In the event of such a failure in a semi-automated frost temperature controller, it is generally not pre-conditioned, but is replaced directly, because the defrosting temperature will also change when adjusting the temperature difference or temperature range.
3) When the thermostat leaks, the thermostat can be removed, cut from the sealing at the front end of the thermostat, and the capillary tube can be welded and repaired by pressing, leak detection, leak filling, vacuuming and filling of thermostat through the three-way repair valve. The repaired thermostat should be loaded into the refrigerator for testing, and whether the thermostat needs to be replenished or released according to the correspondence between the temperature in the box and the start-up and shutdown. Due to the complicated repair work of the leakage fault of the thermostat, the charge of the thermostat is not easy to control, and the method of replacing new parts is mostly used during on-site maintenance.
(3) The replacement of the thermostat should be replaced when the thermostat is invalid by the above method. When replacing. New products of the same specification should be used as much as possible, but if they are not available, they can also be substituted with other specifications. When substituting, it should be noted that the thermostat of the direct-cooled refrigerator is interchangeable with the direct-cooled type, and the thermostat of the intercooled refrigerator should be interchangeable with the intercooled type, and the temperature controller of the same star should be used when interchangeable. When replacing, for the thermostat with two connectors, only the two wirings need to be directly connected, while the thermostat with three connectors should pay attention to the nature of the connectors. The method of identifying the connector is to put the thermostat into the freezer of the refrigerator, place it in a low temperature environment below 12 °C for more than ten minutes, and use a multimeter to measure the two unpassable terminals that are the control terminals of the compressor. After identifying the temperature control joint, connect the two wirings of the compressor circuit to the control terminal, and the other wire to the remaining terminal.
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