This article explains how the SCS Controller alarms work and the actions that you may take to resolve them.
| Fault code | Fault | Possible causes and actions |
| dor * | Door Open |
The door has been left open. Closing the door will clear this fault. The door may not be closed properly due to sagging and may require adjustment.
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| AL15 | Excessive Condenser Overtemp | The condenser has seen multiple overtemperature conditions in a short space of time. Check that nothing is blocking the condenser e.g. boxes, and then reset by power cycling. If this fault continues to happen, check that the condenser fan is functioning correctly. |
| AL17 | NTC Failure | Either the main temperature sensor probe or the condenser temperature probe (if fitted) has failed. The temperature probe needs replacing. The system will not run while this fault is present. |
| AL19 | Refrigeration Failure | The compressor has run continuously for the configured time without reaching the setpoint temperature Multiple possibilities, preventing the system from achieving temperature. In all FW Versions prior to 1574, the system will not reset by power cycling, only by writing to the “Clear Terminal Alarm” parameter. In all FW versions from 1574 onward, the system can also be reset by power cycling |
| AL20 | Return Air Under Temperature | The temperature has dropped below the normal mode setpoint by a specified amount The product temperature keeps getting colder, even when the compressor is turned off. Check the compressor is correctly wired, and that the “Compressor State” parameter is set correctly. Can also be due to an external secondary compressor relay failure. |
| AL21 | Compressor Excessive Starts ** | The compressor has had repeated over temperature trips equaling the high temperature lockout count, within the specified period (This alarm is disabled by default. Parameter access is available upon request). The condenser sensor keeps seeing a high temperature. Check the condenser is not blocked, and the condenser fan is running. |
| AL22 | Triac S1 Overcurrent | The loading on S1 draws too much current. A high current component, such as the compressor, has incorrectly been connected to the S1 output. Check the wiring. |
| AL23 | Triac S2 Overcurrent | The loading on S1 draws too much current. A high current component, such as the compressor, has incorrectly been connected to the S1 output. Check the wiring. |
| AL27 | Other Sensor Failure ** | A sensor other than the return-air-sensor has failed. The sensor needs replacing. The system however will continue to run by ignoring this sensor. |
| AL28 | No Downward tendency lockout ** | The NDT defrost has been blocked the maximum number of times. There could be multiple possibilities that are preventing the system to reach its desired temperature. Most likely causes are frozen evaporator coils, low refrigerant charge or slow fan speed. |
| AL29 | Excessive Overpressure Trips *** | The compressor has had repeated over pressure trips equaling the Over pressure lockout count within the specified period. (This alarm is disabled by default. Parameter access is available upon request). The compressor is faulty or requires servicing. The condenser coil may be blocked and may require cleaning. |
| AL30 | Excessive Short Defrosts *** | The defrost initiation probe has repeatedly triggered defrosts within the min allowable time between defrosts, equaling the Excessive Defrosts Lockout Count. (This alarm is disabled by default. Parameter access is available upon request). The defrost initiation probe is reading a low value within a short time of the compressor turning on. Check that the probe is not touching the evaporator coils, and that the evaporator fan is running. |
* FW version prior to 1574 used fault code 1
** FW version 1580 onwards
*** FW version 1700 onwards