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This post was last edited by yinkuilin6868 on February 24, 2016, at 15:41. Nine questions and answers regarding common compressor malfunctions. 1. The compressor suddenly stops during operation: The reasons are: (1) The suction pressure is too low, falling below the lower limit set by the pressure relay； (2) Excessively high exhaust pressure causes the high-pressure relay to activate and cut off power ； (3) Oil pressure is too low; the oil pressure relay operates ； (4) Motor overload; thermal relay activates ； Exclusion methods: (1) Check the cause; if it is a pipe blockage, clear the pipe, and if there is insufficient refrigerant in the system, top it up ； (2) Check the cooling capacity or airflow of the condenser ； (3) Inspect the pipelines of the oil transfer system and the oil pumps ； (4) Check whether the power supply voltage is too low or the cooling load is excessive ； The reasons for excessive exhaust compression include: (1) Insufficient cooling water flow in the water-cooled condenser, or insufficient cooling air flow in the air-cooled condenser ； (2) Excessive scale on the surface of the condenser tube bundle or too much oil buildup, resulting in difficulty in heat dissipation ； (3) There is air in the refrigeration system ； (4) Excessive refrigerant charging ； (5) A valve in the exhaust pipe malfunctioned, resulting in excessive pressure ； Exclusion methods: (1) Check whether the valve is fully open, increase the water supply, or check the motor voltage and speed as well as whether the drive belt is too loose ； (2) Clean scale and scrub off oil stains to keep the surface of the condenser tube arrays clean ； (3) Release air ； (4) Remove excess refrigerant ； (5) Check and adjust the valve ； 3 Causes of wet compression in compressors: (1) Malfunction of the thermal expansion valve, resulting in excessive opening ； (2) The solenoid valve fails, causing a large amount of refrigerant to enter the evaporator coils after shutdown; this refrigerant then enters the compressor when the machine is started up again ； (3) Excessive amount of refrigerant is charged into the system ； (4) The temperature sensing bulb of the thermal expansion valve was loose and not secured, resulting in an increased opening degree of the thermal expansion valve ； Exclusion method: (1) Close the supply valve and inspect the thermal expansion valve ； (2) Service solenoid valve ； (3) Release excess refrigerant ； (4) Check the binding of the temperature sensor bulb ； The reasons for compressor seizure are: (1) There are dirt and impurities in the lubricating oil ； (2) Blockage in the oil pump delivery pipe causes a lack of oil in the cylinder, resulting in the piston seizing ； (3) The shank pin that inserts the main gear of the oil pump into the crank broke, resulting in a loss of oil supply to the oil system ； Exclusion method: (1) Replace with new lubricant ； (2) Inspect the oil pump pipeline ； (3) Overhaul and replace the main gear shaft of the oil pump ； The reasons for abnormal noises in the 5-cylinder engine are: (1) The dead center clearance in the cylinder is too small ； (2) Excessive clearance between the piston pin and the rod bushings ； (3) Valve disc fracture ； (4) Oil shock noise caused by oil splashing on the crank crankpin or the big end of the connecting rod ； Exclusion methods: (1) Adjust the thickened cylinder gasket ； (2) Replace the piston pin or bushing ； (3) Stop the machine immediately and replace the valve disc ； (4) There is no need to shut down the system for a short period of time; shutdown for inspection is only required if it needs to be stopped for several minutes or more ； 6. Causes of noises in the crankcase: (1) Loose connecting rod nuts ； (2) Excessive clearance in the big-end bearing of the connecting rod ； Exclusion method: (1) Shut down and retighten ； (2) Replace tiles ； Reasons why the compressor fails to start include: (1) Poor contact or blown fuses due to a power outage ； (2) Poor contact of the vertical contacts of the starter ； (3) The temperature controller is out of adjustment or malfunctioning ； (4) Improper adjustment of the pressure relay ； Exclusion methods: (1) Check the power supply and fuse ； (2) Check the starter and wipe the contacts clean with gauze ； (3) Check the temperature indication position and inspect each component ； (4) Check each component of the pressure relay or its setting values ； The reasons for insufficient cooling capacity in a 8-compression mechanism are: (1) worn piston rings or an excessively large gap between the piston and the cylinder due to wear ； Exclusion methods: (1) Replace with new piston rings or repair and replace the components ； The reasons for noise in the coupling between the compressor and the motor are: (1) Improper fit between the compressor and the motor coupling ； (2) Improper fit between the key and keyway of the coupling ； (3) The elastic ring of the coupling is loose or damaged ； (4) Belt is too loose ； (5) Loose fit between the inner hole of the coupling and the shaft ； Troubleshooting method: (1) Reassemble according to the correct assembly requirements ； (2) Adjust the fit between the key and the keyway, and replace the key ； (3) Tighten the elastic ring or replace it with a new one ； (4) Adjust the tension belt ； (5) Adjust and tighten the coupling ；