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Nexus / Nexus+ Troubleshooting

Applies to: CCTSL# · CCTSLW+ · C155

Initialisation — first time setup​

If the Nexus screen powers on but shows no AC or zone information after installation:

  1. Ensure the C225 CPU is powered via the CT24ACE transformer
  2. Confirm the Cat5e cable runs from the iZone Net port on the C225 to the Nexus screen
  3. On the Nexus, go to Setup → Find CPU to scan for the C225
  4. Once found, complete the zone configuration via Setup → Configure AC

Screen is frozen​

The Nexus touch screen is unresponsive to touch input.

Steps to resolve:

  1. Hold the reset button on the back of the Nexus screen for 5 seconds to force a reboot
  2. If the screen does not respond to the reset button, power cycle the C225 CPU by disconnecting the CT24ACE transformer for 10 seconds
  3. If freezing occurs repeatedly, check for a firmware update: Setup → About → Check for Update

Screen continuously reboots without being touched​

The Nexus reboots in a loop without user input.

Steps to resolve:

  1. Check the Cat5e cable between the C225 and the Nexus for damage or a loose connector
  2. Try a different iZone Net port on the C225
  3. If the rebooting continues, the screen unit may need replacement — contact your installer

Screen is beeping​

The Nexus emits a beeping sound.

Steps to resolve:

  1. Beeping typically indicates a loss of communication between the screen and the C225
  2. Check the Cat5e cable and re-seat both ends
  3. Verify the C225 is powered and the status LED is active
  4. If communication is restored, the beeping will stop automatically

Screen flickering or ghosting (display fluctuation)​

The display shows visual artefacts, flickering, or ghost images.

Steps to resolve:

  1. Check the Cat5e cable — a damaged or poorly terminated cable causes display issues
  2. Replace the cable between the C225 and the Nexus
  3. Ensure the cable is not running parallel to high-voltage mains cables (maintain at least 100mm separation)
  4. If the issue persists after cable replacement, the screen may need replacement

Missing AC icons on the screen​

The Nexus home screen is missing the air conditioning control icons.

Steps to resolve:

  1. Go to Setup → Services and check that the AC service is enabled and not hidden
  2. If the AC service is not listed, go to Setup → Find CPU to re-detect the C225
  3. Confirm the C325# AC interface module is correctly clipped onto the C225

Text showing but icons have no or distorted graphics​

Text labels appear normally but icons are missing or look corrupted.

Steps to resolve:

  1. This usually indicates a partial or interrupted firmware update
  2. Go to Setup → About → Check for Update and install the latest firmware
  3. If the option is unavailable, perform a factory reset: Setup → Factory Reset (installer password required), then recommission

No Comms — Screen → CCPU message​

The screen displays a No Comms: Screen → CCPU error.

Steps to resolve:

  1. Check the Cat5e cable connection from the C225 iZone Net port to the Nexus
  2. Try a different iZone Net port on the C225
  3. Reboot the C225 by disconnecting the CT24ACE transformer for 10 seconds
  4. If using a CNEMK Network Extension Kit, verify it is correctly powered and wired

Actual temperature shows zero in all zones (Scrooge mode)​

All zones display 0°C as the actual temperature.

Steps to resolve:

  1. This is caused by Scrooge mode being active, which disables zone temperature reporting to reduce wireless sensor battery usage
  2. To disable: Setup → Configure AC → Options → Scrooge Mode → Off
  3. Wireless sensors (CRFS#) may need a minute to report temperatures again after Scrooge mode is turned off

How to set up schedules and favourites with zone temperature sensors​

  1. Ensure wireless sensors (CRFS#) are paired and showing live temperatures for each zone
  2. Go to Setup → Schedules and create a new schedule
  3. Set the target temperature for each zone individually within the schedule
  4. Favourites with sensor-based targets can be saved from Home → Favourites → Save Current State

How to hide and unhide services​

  1. Go to Setup → Services
  2. Tap the service you want to hide or show
  3. Toggle the Visible option on or off
  4. Hidden services do not appear on the home screen but remain functional