No Display — Slave thermostat screen is blank

What does No Display mean?

The slave thermostat display remains blank even after 24 VAC power has been applied. This indicates that electrical power is not reaching the slave thermostat or there's an issue with its power circuit.

• Power is not reaching the slave thermostat.
• Low voltage from the 24 VAC transformer (below 22-30 VAC).
• Wiring issues between the 24 VAC transformer and the damper actuator, or a faulty transformer.
• Low or unsteady 10 VDC across the red and white wires at the slave thermostat connector board.
• Improperly seated or defective ribbon cable, or a defective wiring connector board or damper actuator.

Click steps to track your progress.

1. 1

   At the damper actuator, check that 24 VAC is being supplied from the power transformer, ensuring it is within 22-30 VAC.

2. 2

   Check all wiring connections between the 24 VAC transformer and the damper actuator, and replace the transformer if necessary.

3. 3

   At the slave thermostat wiring connector board, check for approximately 10 VDC (steady) across the red and white wires from the damper actuator.

4. 4

   Check the continuity of the 5-conductor wire running between the slave thermostat wiring connector board and the damper actuator.

5. 5

   Ensure the slave thermostat ribbon cable is properly seated in the wiring connector board by disconnecting and reconnecting it.

6. 6

   If the display remains blank, refer to the 'Slave Thermostat Wiring' section on page 9 for further checks on the slave thermostat wiring connector block and ribbon cable.