Error 9 warns of a communications failure between the gateway and the Airzone system. The system loses communication with the gateway and therefore with the AC unit. The system will open all its zones and disable control from the system's thermostats, thus allowing the AC unit to operate from the manufacturer's thermostat. To resolve this issue, follow the steps below:

Check that the gateway is properly connected to the main control board's air conditioning unit port. You can consult the AC unit gateway's technical fact sheet (gateways).

If the wiring is correct, check that the status of the connected gateway's LEDs is correct. To do so, also make use of your gateway's technical fact sheet.

If the LEDs' status is correct, measure the voltages in the AC unit bus. To do so, follow the instructions at: ( What are the correct voltages in the AC unit bus? ).

If the voltages are correct, check whether the system detects the AC unit gateway. To do so, go to the system information menu and check what devices are in the system:

In the case of a Blueface thermostat: See Blueface Thermostat User Settings Menu ( Easyzone main controller - Flexa 3.0 - Installation manual ).

In the case of a Think thermostat: See System advanced settings ( Easyzone main controller - Flexa 3.0 - Installation manual ).

If the problem has not been solved, see Problems with the AC Unit ( I have everything installed and associated. I switch on a zone and it does not operate ).