bulk reef heater controller help

[Caesar_corals]

hello my bulk reef heater controller is saying Hl what does this mean?

 

[cvrle1]

Over-temperature Alarm:when measured temperature exceeds the measuring range (less than -50°C /-58° F or higher than 99 °C/210 ° F), the controller will initiate over-temperature alarm mode, and cancel all the actions. The buzzer will alarm, LED displays HL. Buzzer alarm could be dismissed by pressing any key. When temperature returns to measuring range, the system will return to normal working status

 

[Caesar_corals]

Over-temperature Alarm:when measured temperature exceeds the measuring range (less than -50°C /-58° F or higher than 99 °C/210 ° F), the controller will initiate over-temperature alarm mode, and cancel all the actions. The buzzer will alarm, LED displays HL. Buzzer alarm could be dismissed by pressing any key. When temperature returns to measuring range, the system will return to normal working status

thank u