Atlas Copco QAS 108 troubleshooting: 45 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
Atlas Copco QAS 108 — full specs, parts & maintenance.
| Symptom | Cause | Remedy |
|---|---|---|
| Alternator does not excite. | Blown fuse. | Replace fuse. |
| After being excited alternator does not excite. | Insufficient residual voltage. | |
| Low voltage at no load. | No residual voltage. | |
| High voltage at no load. | Connections are interrupted. | Check connection cables as per attached drawings. |
| Lower than rated voltage at load. | Voltage potentiometer out of setting. | Reset voltage. |
| Higher than rated voltage at load. | Intervention by protection. | Check rpm. |
| Unstable voltage. | Winding failure. | Check windings. |
| The starter motor turns the engine too slowly | - Battery capacity too low. - Bad electrical connection. - Fault in starter motor. - Wrong grade of lubricating oil. | |
| The engine does not start or is difficult to start | - Starter motor turns engine too slowly. - Fuel tank empty. - Fault in fuel control solenoid. - Restriction in a fuel pipe. - Fault in fuel lift pump. - Dirty fuel filter element. - Air in fuel system. - Fault in atomisers. - Cold start system used incorrectly. - Fault in cold start system. - Restriction in fuel tank vent. - Wrong type or grade of fuel used. | |
| Not enough power | - Restriction in a fuel pipe. - Fault in fuel lift pump. - Dirty fuel filter element. - Restriction in air filter/cleaner or induction system. - Air in fuel system. - Fault in atomisers or atomisers of an incorrect type. - Restriction in fuel tank vent. - Wrong type or grade of fuel used. - Restricted movement of engine speed control. - Restriction in exhaust pipe | |
| Engine hard to start or will not start. | Dirty or faulty injection nozzles; Crankcase oil too heavy; Improper type of fuel; Water, dirt or air in fuel system; Clogged fuel filter; Engine overloaded; Intake air restriction; Clogged fuel filter | Consult authorized diesel repair station; Use cold weather starting aids; Verify correct starting procedure; Use oil of proper viscosity; Drain, flush, fill, and bleed system; Replace filter element; Reduce load; Service air cleaner; Replace filter elements; Use proper fuel |
| Engine overloaded. | Reduce load | |
| Intake air restriction. | Service air cleaner | |
| Clogged fuel filter. | Replace filter elements; Drain, flush, fill, and bleed system; Replace fuel filter element | |
| Improper type of fuel. | Use proper type of fuel for operating conditions; Use proper fuel | |
| Overheated engine. | See “Engine Overheats” | |
| Low coolant temperature. | Remove and check thermostat; Warm up engine to normal operating temperature | |
| Engine knocks. | See “Engine Overheats” | |
| Defective thermostat. | Remove and check thermostat; Check water temperature with thermometer and replace, if necessary | |
| Engine runs irregularly or stalls frequently. | Dirty or faulty injection nozzles | See your authorized servicing dealer or engine distributor |
| Defective temperature gauge or sender. | Check gauge, sender and connections | |
| Engine emits white smoke. | Engine out of time | See your authorized servicing dealer or engine distributor |
| Engine out of time. | See your authorized servicing dealer or engine distributor | |
| Engine emits black or gray exhaust smoke. | Turbocharger not functioning | See your authorized servicing dealer or engine distributor |
| Low coolant level. | Fill radiator to proper level, check radiator and hoses for loose connections or leaks; Check thermostat | |
| Faulty radiator cap. | Have service company check | |
| Stretched poly-vee belt or defective belt tension. | Check automatic belt tensioners and check belts for stretching. Replace as required | |
| Low engine oil level. | Check oil level. Add as required | |
| Cooling system needs flushing. | Flush cooling system | |
| Engine overheats. | Incorrect grade of fuel | Use correct grade of fuel |
| Clogged or dirty air cleaner. | Service air cleaner | |
| Improper valve clearance. | See your authorized servicing dealer or engine distributor | |
| Injection nozzles dirty. | See your authorized servicing dealer or engine distributor | |
| Defective turbocharger. | See your authorized servicing dealer or engine distributor | |
| High fuel consumption. | Low engine temperature | Check thermostat; Check water temperature with thermometer and replace, if necessary |
| Engine shuts down after approx. 15 seconds. | Poor connection on oil or coolant temperature switches | Check connections; Check controller DIP switches |
| Alternator doe not excite. | Blown Fuse. Insufficient Voltage. No residual Voltage. | Replace Fuse. Increase speed by 15%. For an instant apply on the + and – terminals of the electronic regulator a 12 V battery voltage with a 30 ? resistor in series respecting the polarities. |
| After being excited, alternator does not excite. | Connections are interrupted. Low voltage at no load. Voltage potentiometer out of setting. Intervention of protection. Winding Failure. | Check connection cables per drawings. Reset Voltage. Check RPM. Check Windings. |
| Higher than rated voltage. | Voltage potentiometer out of setting. Failed regulator. | Reset Voltage. Substitute regulator. |
| Incorrect starting procedure. | Verify correct starting procedure. | |
| No fuel. | Check fuel in tank and manual shut-off valve. | |
| Exhaust restricted. | Check and correct exhaust restriction. | |
| Fuel filter plugged or full of water. | Replace fuel filter or drain water from filter. | |
| Injection pump not getting air or fuel. | Check fuel flow at supply pump or bleed fuel system. | |
| Engine cranks but will not start. | Fau |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: Blown fuse.. See the table for the matching fixes.
Documented causes: Insufficient residual voltage.. See the table for the matching fixes.
Documented causes: No residual voltage.. See the table for the matching fixes.