[Mechanical Equipment Technology Edition] Daily Question 201708014: Refrigeration Faults

It is commonly seen when there are problems with the sealing of the refrigeration system

Common compressor faults and troubleshooting methods: I. Sudden shutdown of the compressor during operation: 1. Reasons for the sudden shutdown of the compressor while it is running include: (1) Too low suction pressure, 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) Low oil pressure; the oil pressure relay activates ； (4) Motor overload, thermal relay activates ； 2. Methods for troubleshooting sudden shutdowns of the compressor during operation: (1) Identify the cause; if it is due to a blocked pipeline, clear it, and if there is a shortage of 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 ； II. Excessive exhaust compression 1. The reasons for excessive exhaust compression are: (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 filling ； (5) A failure in the valve within the exhaust pipeline causes excessive pressure ； 2. Methods to address excessive exhaust compression: (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 bundles clean ； (3) Release air ； (4) Remove excess refrigerant ； (5) Check and adjust the valve ； III. Wet stroke of the compressor 1. The reasons for a wet stroke in the compressor are: (1) Failure of the thermal expansion valve, resulting in an excessive degree of 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 restarted ； (3) Excessive amount of refrigerant pumped 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 ； 2. Methods to eliminate the wet stroke of the compressor: (1) Close the liquid supply valve and inspect the thermal expansion valve ； (2) Service solenoid valve ； (3) Release excess refrigerant ； (4) Check the binding of the temperature sensor element ； IV. Compressor jamming 1. The reasons for compressor jamming are: (1) Dirt and impurities in the lubricating oil ； (2) The oil pump’s oil delivery pipe is blocked, resulting in a lack of oil in the cylinder and the piston getting stuck ； (3) The shaft pin into which the main gear of the oil pump is inserted broke, resulting in a loss of oil supply to the oil system ； 2. Methods to resolve a stuck compressor: (1) Replace with new lubricating oil ； (2) Inspect the oil pump pipeline ； (3) Overhaul and replace the main gear shaft of the oil pump ； V. Abnormal noises in the cylinder 1. The reasons for abnormal noises in the cylinder are: (1) The dead center clearance in the cylinder is too small ； (2) Excessive clearance between the piston pin and the rod bearing bushings ； (3) Valve disc fracture ； (4) Oil impact noise caused by oil splashing on the crank crankpin or the big end of the connecting rod ； 2. Abnormal noises in the cylinder (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 ； VI. Noise in the crankcase 1. The reasons for noise in the crankcase are: (1) Loose connecting rod nuts ； (2) Excessive clearance in the big-end bearing of the connecting rod ； 2. Methods to eliminate noises in the crankcase: (1) Shut down the machine and tighten the connections again ； ......

Common compressor faults and troubleshooting methods: I. Sudden shutdown of the compressor during operation: 1. Reasons for the sudden shutdown of the compressor while it is running include: (1) Too low suction pressure, 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) Low oil pressure; the oil pressure relay activates ； (4) Motor overload, thermal relay activates ； 2. Methods for troubleshooting sudden shutdowns of the compressor during operation: (1) Identify the cause; if it is due to a blocked pipeline, clear it, and if there is a shortage of 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 ； II. Excessive exhaust compression 1. The reasons for excessive exhaust compression are: (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 filling ； (5) A failure in the valve within the exhaust pipeline causes excessive pressure ； 2. Methods to address excessive exhaust compression: (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 bundles clean ； (3) Release air ； (4) Remove excess refrigerant ； (5) Check and adjust the valve ； III. Wet stroke of the compressor 1. The reasons for a wet stroke in the compressor are: (1) Failure of the thermal expansion valve, resulting in an excessive degree of 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 restarted ； (3) Excessive amount of refrigerant pumped 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 ； 2. Methods to eliminate the wet stroke of the compressor: (1) Close the liquid supply valve and inspect the thermal expansion valve ； (2) Service solenoid valve ； (3) Release excess refrigerant ； (4) Check the binding of the temperature sensor element ； IV. Compressor jamming 1. The reasons for compressor jamming are: (1) Dirt and impurities in the lubricating oil ； (2) The oil pump’s oil delivery pipe is blocked, resulting in a lack of oil in the cylinder and the piston getting stuck ； (3) The shaft pin into which the main gear of the oil pump is inserted broke, resulting in a loss of oil supply to the oil system ； 2. Methods to resolve a stuck compressor: (1) Replace with new lubricating oil ； (2) Inspect the oil pump pipeline ； (3) Overhaul and replace the main gear shaft of the oil pump ； V. Abnormal noises in the cylinder 1. The reasons for abnormal noises in the cylinder are: (1) The dead center clearance in the cylinder is too small ； (2) Excessive clearance between the piston pin and the rod bearing bushings ； (3) Valve disc fracture ； (4) Oil impact noise caused by oil splashing on the crank crankpin or the big end of the connecting rod ； 2. Abnormal noises in the cylinder (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 ； VI. Noise in the crankcase 1. The reasons for noise in the crankcase are: (1) Loose connecting rod nuts ； (2) Excessive clearance in the big-end bearing of the connecting rod ； 2. Methods to eliminate noises in the crankcase: (1) Shut down the machine and tighten the connections again ； ......

In summer, with high ambient temperatures, electrical components are prone to malfunctions caused by rising temperatures due to poor heat dissipation.

The condensation effect is poor, and the temperature of the lubricating oil is high

Due to high temperatures, the exhaust temperature rises and the exhaust pressure becomes too high, resulting in overheating and overpressure; excessive load leads to overcurrent. Again, high temperatures are the cause of high lubricant temperatures

The inlet and outlet water temperatures of the system increase accordingly; this temperature rise leads to scaling on the inner surfaces of the oil coolers, condensers, and pipes, resulting in poor heat exchange efficiency. This results in insufficient cooling capacity, as well as faults such as fluorine and oil leakage.