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CEXT Troubleshooting

Applies to: CEXT (Zone Extender)

Zones 9–14 not responding​

Zones connected to the CEXT zone extender are unresponsive.

Steps to resolve:

  1. Confirm the CEXT is correctly plugged into the expansion port on the C225 CPU
  2. Check that zone motors are wired to CEXT ports starting at Zone 9 consecutively
  3. Verify the CT24ACE transformer is providing ~24VAC — the CEXT is powered through the C225
  4. In the iZone app, go to Setup → Configure AC and confirm the zone count includes the CEXT zones

CEXT not detected by the C225​

The system only shows 8 zones and the CEXT zones are absent.

Steps to resolve:

  1. Power off the system by disconnecting the CT24ACE transformer
  2. Re-seat the CEXT firmly onto the C225 expansion connector
  3. Power the system back on and allow 30 seconds for zone detection
  4. If still not detected, try a different CEXT unit to rule out a hardware fault