StU or STUCK ON Message
A Pump appears to be "Stuck" (StU) ON, and the Water is Too Hot.
If the spa is configured with the GFCI Trip Feature disabled or the system is not capable of the feature (GL Systems) the spa will not be able to shut itself down via a GFCI trip. In this case, if the extreme conditions are determined, the spa will display the StU message until the spa is shut down It will also set the HOt flag (HOt does not appear in the display).
In this condition, the water temperature is most likely dangerously hot!
If the spa is powered up again the HOt message will appear on the display and the spa will not be allowed to operate until a technician evaluates the spa and resets the HOt fault by powering up in Test Mode (DIP Switch A1 on the System Board).
Note: The StU or HOt messages indicate the spa IS or WAS in an extremely serious condition. It may be possible for the stuck relay to free itself after the power cycle, but the spa cannot clear the the HOt message without starting up in Test Mode first. A service technician must carefully evaluate the pumps and circuit board before allowing the spa to run again.
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