Atlas Copco U190 PACE KD WUX, Installation Manual, Page: 76 / 92

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Problem: Pressure in air receiver rises above maximum and causes safety valve to blow.
Problem: After working some time, the unit stops through a shutdown switch.
Problem: Air and oil mist expelles from air filters immediately after stopping.
Possible faults Corrective actions
Regulating valve (RV) opens too late or its ball valve spring is broken. Have regulating valve removed and inspected by an Atlas Copco Service representative.
Air leaks in regulating system.
Check hoses and their fittings. Stop leaks; replace leaking hoses.
Air intake throttle valve does not close for some reason. Remove air filters, air intake manifold and throttle valve spring seat. Withdraw the valve and
inspect. Replace parts where necessary. Caution: the spring seat is fixed with 4 short and 2 long
setscrews: first remove the short screws, then release the spring tension unscrewing the long
ones.
Minimum pressure valve malfunctioning. Remove and inspect valve.
Blow-off valve malfunctioning. Remove and inspect valve.
Possible faults Corrective actions
Engine oil pressure too low. Refer to the engine instruction manual.
Compressor or engine overheating. See corrective actions “Compressor overheating”.
Fuel tank contains insufficient fuel. Fill fuel tank.
Low coolant level. Top up cooling system.
Possible faults Corrective actions
Check valve at element outlet. Remove and inspect. Replace if necessary. Replace air filter elements and safety cartridges.
Check the oil level and add oil if necessary. Run the compressor for a few minutes, stop and
recheck oil level.
Plunger of oil stop valve jammed. Remove and inspect. Replace if necessary. Replace air filter elements and safety cartridges.
Check the oil level and add oil if necessary. Run the compressor for a few minutes, stop and
recheck oil level.