Troubleshooting Hunter Pro-C Module Failures After a Storm

Post-Storm Symptoms: Zones 4–8 Dead

After a thunderstorm, a Hunter Pro-C controller shows voltage on zones 1–3 but none on zones 4–8 (two expansion modules). Swapping modules doesn't help.

Likely Cause: Main Board Damage

The Pro-C's main board communicates with expansion modules via a backplane connector. A power surge can damage the main board's output drivers or communication circuitry while leaving the modules intact.

Reset Attempt

1. Remove the 9 V backup battery.
2. Disconnect AC power for 60 seconds.
3. Reconnect power without the battery.
4. Test zone voltages again.

If No Voltage Returns

The main controller unit is likely fried. Replacement is recommended. Hunter ICC2 or Pro-HC controllers are modern equivalents with better surge protection.

Surge Protection Tip

Install a surge protector (e.g., Intermatic IG1240RC3) on the controller's 120 V input and consider a low-voltage surge suppressor on the field wire common line.