Hardie TC-15B Manual Mode Fails – Common Wire Break Likely

If no zones activate in manual mode despite 27 VAC at transformer and direct wire testing, the common field wire is likely broken.

Diagnosis

• Common wire carries return path for all valves.
• Break in common wire disables every zone.
• Individual hot wire break affects only one zone.

Test

1. At controller, disconnect common and one zone wire.
2. Connect them directly to transformer terminals.
3. If solenoid clicks, valve and zone wire are good—common wire is suspect.
4. Trace common wire path for cuts, corrosion, or loose splices.