974 StarCool Alarm Codes And Actions

974 Sensor bus sup HI
Description Controller Internal Voltage Reference Fault
Cause Indication of controller internal voltage reference fault
Trouble
shooting		 Possible causes:
  • Defective 12V power supply on main controller.
  • Defective main controller.
  • Short circuit between 24V DC and 12V DC
Accompanied alarms:
  • There may be sensor alarms, AL 3XX.
  • AL 801 will be activated during FT- or PTI test.
Trouble shooting:
  1. Check if there are other active (sensor) alarms. Clear these alarms fi rst using their trouble shooting.
  2. Check voltage level of 24V DC and 12V signals to see if power supply has an short circuit or other damages. If the correct voltage is measured at X11 then circuit is defective.
Replace main controller.
Criteria Reference voltage sensor bus above 14V DC

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