Controller Microprocessor Lock-up: What it is and How to Fix it

A common problem with all brands of solid-state type controllers is called “microprocessor lockup.” This is where, after a power surge or spike, the microprocessor stops processing data. In most cases, the lockup can be cleared by simply removing the backup battery and disconnecting the incoming power to the controller for 5-10 minutes. Turn the power back on and operate several valves manually using the controller, set the Date and Time. If this unlocks the microprocessor, chances are that the controller will operate normally.

If this doesn’t work, you’ll need to do a complete “Reset” on the controller, this will also clear ALL programming in the controller. Hunter controllers have non-volatile memory, which means that the controller’s programming will remains in place even after the power and battery have been removed, so if you want to clear out all the programming, you will need to follow the same steps. To do this, leave the power on to the controller, open the controller’s front panel and locate the controller’s “Reset” button on the back of the front panel.

Simultaneously press and hold down the minus button, right arrow button, and PRG button on the controller’s front panel, depress the reset button with a paperclip. Hold the “Reset” button down for 1-2 seconds, release the “Reset” button and continue to hold the minus button, right arrow button, and PRG button down for 3-4 seconds more, release the three buttons and the current time should change to a flashing 12:00. When the display shows a flashing 12:00, you have successfully reset the controller and erased all the memory.

These simple steps can save you the time and hassle of replacing a controller that may not be the source of your system’s problem.