What are the most common failures of air conditioning compressors?

Update:25 Apr 2021
Summary:

The air conditioning system has four major parts: compr […]

The air conditioning system has four major parts: compressor, condenser, evaporator and throttling components. Shanghai Zhaoxue Refrigeration Equipment Co., Ltd. is Industrial Refrigeration System Manufacturers,we supply condensing units air conditioning.Today we will share the knowledge about the most common faults of compressors.
(1) the refrigeration compressor cannot start normally
  Overhaul ideas
  1. First, check whether it is caused by low power supply voltage or poor connection of the motor circuit.
   If it is determined that the grid voltage is too low, restart after the grid voltage returns to normal: If the line is in poor contact, the connection between the line and the motor should be detected and repaired.
  2, check whether the exhaust valve plate is leaking.
  If the exhaust valve is damaged or the seal is not tightly leaked, the pressure in the crankcase will be too high, causing it to fail to start normally. Just replace the exhaust valve plate and the sealing line.
   3. Check whether the energy adjustment mechanism is out of order.
   Mainly check whether the oil supply pipeline is blocked, the pressure is too low, the oil piston is stuck, etc. and repair it according to the cause of the failure.
   4. Check whether the temperature controller is damaged or out of adjustment.
   If it is out of adjustment, the temperature controller should be adjusted; if it is damaged, it should be repaired or replaced.
   5. Check whether the pressure relay is out of order.
   Check the pressure relay and reset the pressure parameters.
(2)no oil pressure
  Overhaul ideas
   1. Check whether there is oil leakage or blockage at the connection of the oil pump piping system.
   The joint should be tightened; if it is blocked, the oil pipeline should be cleared.
  2. Is the oil pressure regulating valve opened too much or the spool falls off?
   If the oil pressure regulating valve is improperly adjusted, the oil pressure regulating valve should be adjusted and the oil pressure should be adjusted to the required value; if the spool falls off, the spool must be reinstalled and tightened firmly.
  3. If there is too little oil in the crankcase or there is ammonia liquid, the oil pump will not enter oil.
   If there is too little oil, refuel in time; if it is the latter, shut down in time to remove ammonia.
  4. The oil pump is severely worn. The gap is too large, causing the oil pressure to fail.
  In this case. The oil pump should be repaired, and it should be replaced directly when the fault is serious.
   5. Check whether the connecting rod bearing, main bearing, connecting rod small end bushing and piston pin have been severely worn.
   At this time, the relevant parts should be replaced in time.
   6, the crankcase rear cover gasket is misaligned
   The oil inlet channel of the oil pump is blocked after the misalignment occurs. Disassembly and inspection should be done, and the position of the gasket should be fixed again.
(3) a large amount of foam is generated in the crankcase
  Overhaul ideas
   The lubricating oil in the crankcase foamed and the liquid hit was caused by the following two reasons:
   1. There is a large amount of ammonia liquid mixed in the lubricating oil. When the pressure drops, the ammonia liquid will evaporate and produce a lot of foam.
   For this, the ammonia in the crankcase should be evacuated.
  2. There is too much lubricating oil in the crankcase, and the big end of the connecting rod agitates the lubricating oil, causing a lot of foam.
   In this regard, the excessive lubricating oil in the crankcase should be released to make the oil level reach the specified oil level line.
(4) overhaul ideas for high oil temperature
   1. The shaft and the bush are not properly assembled, and the gap is too small.
   The size of the assembly gap between the shaft and the bush should be adjusted to make the gap meet the standard requirements.
  2. The lubricating oil contains impurities, which causes the bearing bush to be rough.
   For this, the napping bearing should be flattened. And replace with new oil: if the tiles are severely rough, replace with new tiles.
   3. The shaft seal friction ring is installed too tightly or the friction ring is rough.
   The shaft seal friction ring should be readjusted. If the friction ring is severely fluffed, replace it with a new one.
  4. If it is caused by the high temperature of the suction and exhaust of the compression starvation.
   The liquid supply valve of the system should be properly adjusted to restore the suction and exhaust temperature to normal.
(5) the pressure in the crankcase increases
  Overhaul ideas
   1. The piston ring is not tightly sealed.
  The sealing ring of the new piston should be replaced because the seal is not tight, which causes the high pressure to the low pressure.
  2. The exhaust valve is not closed tightly, causing the pressure in the crankcase to rise.
   The air tightness of the exhaust valve seat should be checked. If the seal is not tight, a new valve should be replaced in time.
  3. The tightness of the cylinder liner and the machine base has deteriorated.
   The cylinder liner should be removed, the joints should be cleaned and sealed, and then reassembled.
  4. Too much ammonia enters into the crankcase, and the pressure rises after evaporation.
   As long as the excessive ammonia in the crankcase is evacuated.
(6) the energy regulation mechanism fails
  Overhaul ideas
   1. Check if the oil pressure is too low or the oil pipe is blocked
  If the oil pressure is too low. Adjust and increase the oil pressure; if the oil pipe is blocked, the oil pipe should be cleaned and unblocked.
  2. Is the oil piston stuck?
   The oil piston should be removed for cleaning and the dirty oil should be replaced. Reassemble it correctly.
  3. Is the tie rod and the rotating ring installed incorrectly?
  Causing the rotating ring to be jammed-should focus on checking the assembly of the pull rod and the rotating ring, and repair it until the rotating ring can rotate flexibly.
   4. Check whether it is caused by improper assembly of the oil distribution valve.
   If the ventilation method is used to check whether each working position is appropriate, and then adjust the oil distribution valve again.
(7)the return air heat and waste are too large
  Overhaul ideas
   1. Check whether the ammonia in the evaporator is too small or the opening of the liquid supply valve is too small.
   If the system lacks ammonia, it should be replenished in time; if the liquid supply valve is not adjusted properly, the liquid supply valve should be opened to the appropriate position.
  2. Whether it is due to poor insulation of the return air pipe insulation layer or damp damage.
   The insulation layer should be inspected thoroughly and replaced with new insulation materials.
   3. The suction valve is leaking or ruptured and damaged.
   If the air leakage is slight, the valve plate can be ground to make it no longer leak; if it is broken, the suction valve plate can be directly replaced with a new one.
(8)the suction pressure of the compressor is lower than the normal evaporation pressure
  Overhaul ideas
  1. The opening of the liquid supply valve is too small, which can lead to insufficient liquid supply, so the evaporation pressure will drop.
  For this, just open the liquid supply valve to an appropriate level.
  2. The valve in the suction line is not fully opened or the valve core is off.
   If it is the former, the valve should be fully opened; if the spool falls off, the spool should be reinstalled.
  3. There is a lack of liquid ammonia in the system, even if the pressure valve is opened, the evaporation pressure is still low.
  At this time, an appropriate amount of liquid ammonia should be added according to the actual situation.
  4. The return air pipeline is thin, or there is a "liquid sac" phenomenon in the return air pipeline.
   If the diameter of the pipe is too thin, replace the appropriate return air pipe; if there is a "liquid sac" phenomenon, remove the "liquid sac" section of the air return pipeline and re-weld the pipe.
(9)compressor wet stroke
  Overhaul ideas
   1. When the compressor starts, if the suction valve opens too fast, it will cause a wet stroke.
   Therefore, the suction valve should be opened slowly when starting to avoid wet stroke and damage to the compressor.
  2. If the opening of the liquid supply valve is too large, it will also cause a wet stroke.
  At this time, just turn the liquid supply valve down appropriately.
  3. Return to normal temperature after defrosting in the cold storage.
   The suction valve should be opened slowly, and the operation of the refrigeration compressor should be observed at any time. If the return air temperature drops too fast, you should temporarily stop the opening, and wait for the operation to return to normal, then continue to open slowly.
(10) there is a knocking sound in the crankcase
  Overhaul ideas
   1. Check whether the gap between the big end bush of the connecting rod and the shaft journal is too large.
   At this time, the gap should be adjusted, or directly replaced with new tiles.
  2. If the gap between the main bearing and the main journal is too large.
   This will cause collision and friction, which will produce knocking sound, and the tiles should be repaired or replaced.
   3. Check whether the split pin is broken and the connecting rod nut is loose.
  If yes, replace the cotter pin with a new one and tighten the connecting rod nut.
  4. If the center of the coupling is not right or the keyway of the coupling is loose.
   The coupling should be adjusted or the keyway should be overhauled or replaced with a new key.
   5. The main bearing steel ball is worn out, and the bearing frame is broken.
   For this, replace the bearing with a new one.
(11) the cylinder wall temperature is overheated
  Overhaul ideas
   1. If the oil pump fails, the oil pressure is too low or the oil circuit is blocked.
  Should be shut down for a full overhaul.
  2. Check whether the gap between the piston and the cylinder wall is too small or the piston is off-center.
  At this time, the piston should be adjusted.
   3. The safety block or false cover is not tightly sealed, resulting in high and low pressure gas leakage.
   Measures should be taken to repair and improve the sealing performance.
   4. Check whether the suction temperature is too high.
   Adjust the operation to lower the suction temperature.
   5. If the quality of the lubricating oil is not good, the viscosity is too small.
  Should stop and replace with new lubricating oil.
   6. Check whether the scale in the cooling water jacket is too thick or the amount of water is insufficient.
   If the scale is too thick, it should be removed in time; if the amount of bitter water is insufficient, the amount of cooling water should be increased.
   7. Check whether the suction and exhaust valves are damaged.
  If it is damaged, replace the suction and exhaust valves in time.
   8. Check whether the piston ring has been severely worn.
  If yes, just replace the piston ring with a new one.
(12) the shaft seal is leaking seriously
  Overhaul ideas
   1. Check if the shaft package is poorly matched, causing serious oil leakage in the shaft seal.
   The shaft seal should be assembled correctly.
  2. Check whether the friction surface between the moving ring and the fixed ring has been napped.
   If the fuzz is severe, grind the sealing surface carefully and reassemble it.
  3. If the rubber sealing garden is aging or the tightness is not set properly, oil will leak.
  In this regard, a new rubber garden should be replaced, and the appropriate tightness should be adjusted.
  4. Check whether it is due to the weakening of the elastic force of the shaft seal spring that causes the shaft seal to leak oil.
   The original spring should be removed and replaced with a new one of the same size.
   5. Check whether the sealing performance of the back of the fixing ring and the shaft seal gland has deteriorated.
  For this, the fixing ring should be removed, and the back ring should be cleaned and reassembled.
   6. If the crankcase pressure is too high, adjustments should be made.
   But before stopping, lower the pressure of the crankcase and check whether the exhaust valve is leaking.
(13)shaft seal oil temperature is too high
  Overhaul ideas
   1. Check whether the lubricating oil is insufficient or the oil pipeline is blocked.
  If the oil is insufficient, add lubricating oil in an appropriate amount; if the pipeline is blocked, the oil pipeline should be cleared.
   2. Check whether the lubricating oil is dirty or has deteriorated.
   For this, the filter should be cleaned and replaced with new oil.
   3. Check whether the friction surface of the moving ring and the fixed ring is too tight.
   The elastic strength of the spring should be adjusted appropriately.
   4. The packing gland is too tight.
   The gland nuts should be adjusted evenly to avoid being too tight, resulting in too high shaft seal oil temperature.
   5. Check whether the main bearing assembly clearance is too small.
   For this, the gap should be adjusted appropriately.