Atlas Copco QAS 45 KD troubleshooting: 21 fault codes and symptom-cause-remedy entries from the manufacturer's own service documentation.
Atlas Copco QAS 45 KD — full specs, parts & maintenance.
| Symptom | Cause | Remedy |
|---|---|---|
| Alternator gives 0 Volt | Blown fuse. | Replace fuse. |
| No residual voltage. | Excite the alternator by applying a 12V battery voltage with a 30 W resistor in series on the + and - terminals of the electronic regulator, respecting the polarities. | |
| After being excited the alternator still gives 0 Volt. | Connections are interrupted. | Check connection cables, measure winding resistances and compare with values mentioned in the alternator manual. |
| Low voltage at no load | Voltage potentiometer out of setting. | Reset voltage. |
| Intervention of protection. | Check frequency/voltage regulator. | |
| Winding failure. | Check windings. | |
| High voltage at no load | Voltage potentiometer out of setting. | Reset voltage potentiometer. |
| Failed regulator. | Substitute regulator. | |
| Lower than rated voltage at load | Voltage potentiometer out of setting. | Reset voltage potentiometer. |
| Intervention by protection. | Check frequency/voltage regulator. | |
| Current too high, power factor lower than 0.8; speed lower than 10% of rated speed. | Failed regulator. | Substitute regulator. |
| Rotating bridge failure. | Check diodes, disconnect cables. | |
| Higher than rated voltage at load | Voltage potentiometer out of setting. | Reset voltage potentiometer. |
| Unstable voltage | Speed variation in engine. | Check regularity of rotation. |
| Regulator out of setting. | Regulate stability of regulator by acting on STABILITY potentiometer. | |
| 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.; Restriction in exhaust pipe. | |
| Not enough power | Restriction in a fuel pipe.; Fault in fuel lift pump.; Dirty fuel filter element.; Air in fuel system.; Fault in atomisers or atomisers of an incorrect type.; Restriction in air filter/cleaner or induction system.; Air in fuel system.; Fault in atomisers or atomisers of an incorrect type.; Wrong type or grade of fuel used.; Restricted movement of engine speed control.; Restriction in exhaust pipe.; Engine temperature is too high.; Engine temperature is too low. | |
| Misfire | Restriction in a fuel pipe.; Fault in fuel lift pump.; Dirty fuel filter element.; Air in fuel system.; Fault in atomisers or atomisers of an incorrect type.; Fault in cold start system.; Engine temperature is too high.; Incorrect valve tip clearances. | |
| The pressure of the lubricating oil is too low | Wrong grade of lubricating oil.; Not enough lubricating oil in sump.; Defective gauge.; Dirty lubricating oil filter element. | |
| High fuel consumption | Restriction in air filter/cleaner or induction system.; Fault in atomisers or atomisers of an incorrect type.; Fault in cold start system.; Wrong type or grade of fuel used.; Restricted movement of engine speed control.; Restricted exhaust pipe. |
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: Excite the alternator by applying a 12V battery voltage with a 30 W resistor in series on the + and - terminals of the electronic regulator, respecting the polarities.. See the table for the matching fixes.
Documented causes: Connections are interrupted.. See the table for the matching fixes.