What does the "no AC" message indicate when displayed on a controller?

The "no AC" message on a controller signifies that there is no alternating current (AC) power being supplied to the device. This is a critical indicator as controllers rely on a consistent power source to operate effectively. When this message appears, it usually means that either the power cord is disconnected, there is an issue with the outlet, or there may be a failure within the power supply unit itself. Recognizing this message is essential for troubleshooting and ensuring the proper functioning of an irrigation system. Power issues must be resolved before the controller can manage watering schedules and other automated functions effectively.

In contrast, the other options pertain to different operational states. For instance, if the water supply were disconnected, it would typically indicate a different kind of problem unrelated to power. Similarly, faulty sensors would not necessarily trigger a "no AC" message but could impact system performance in other ways. Lastly, a system in standby mode is operating correctly and has power; it simply means that the system is paused and ready for activation. Understanding these distinctions helps technicians diagnose issues more effectively.