Display is blank or shows “No AC” and the valve does not operate.

Safety: Use caution when working around 120V AC. If unsure, contact an electrician or technician.

Steps:

• Check outlet: Confirm the wall outlet has power by plugging in another device. Reset any tripped GFCI or breaker.
• Verify transformer: Ensure the Clack 24V transformer is plugged in securely. Use a multimeter to measure output voltage; it should match the rating on the transformer label (typically ~24 VAC). Replace the Clack 24V transformer if there is no or low output.
• Inspect low-voltage plug: Confirm the low-voltage plug from the transformer is fully inserted into the control valve power jack.
• Check control board connection: If accessible, verify that the internal power connector on the control board is secure.
• Board replacement: If correct voltage is present at the board but the display remains dead, the control board is likely failed and must be replaced.

Warning: Do not attempt to hard-wire the transformer or bypass safety features. Always use the correct Clack-approved transformer.