Troubleshooting Controllers - Part II:
Correcting a Bad or "Frozen" Display or Programming Malfunctions

A common problem with all brands and types of solid-state controllers is "microprocessor lockup," where after a power surge or spike, the microprocessor stops processing data. In most cases, lockup can be cleared in the field by simply removing the backup battery and disconnecting incoming power to the controller for about 10 minutes. Turn the power back on and operate several valves manually through the controller, set the time and day. If this works, chances are very good the controller will operate normally.

Since the Hunter ICC controller has a non-volatile memory which remains in place even after the power and battery are removed, sometimes you may also want to clear this portion of the controller's memory as well. To do so, leave the power on to the controller, open the controller's front panel and locate the controller's reset button on the back side.

While holding down the reset button with a paper clip or small flat blade screwdriver, simultaneously press and hold down the minus button, right arrow button and PRG button on the controller's faceplate. When the display changes from the current time to a flashing 12:00, you have successfully cleared the controller's memory.

These simple steps – along with those outlined in the "Troubleshooting Controllers – Part I: Quick Tests to Determine if the Controller is Really the Source of the Problem" – can save you the time and hassle of replacing a controller that may not be the source of your system's problem. In upcoming issues, we continue to focus in on this topic with a discussion on troubleshooting field wires and valve solenoids.