AEC TrueTemp Series Operation And Installation Manual page 33

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AEC/Appllcatlon Engineering
Over Temperature
When lit, the controller outputs are disabled and the heaters are de-energized, but the pump
continues circulating fluid to prevent damage to the heaters. The audible alarm sounds when this
indicator lights.
Heater On
When lit, the heaters are energized.
Cooling Valve On
When lit, the cooling solenoid valve is open to allow cooling water into the heat exchanger. This
light is installed only on units with the optional heat exchanger.
Note: Rapidly-cycling, alternating
Heater On and Cooling Valve On
lights indicate an
inefficient process. Perform the Auto-Tune procedure in Section 5-9 on Page 38. For
more information, see Chapter 7 -Troubleshooting on Page 57.
Low Pressure
When lit, the controller outputs are disabled and the heaters are de-energized, but the pump
continues to run to prevent damage to the heater elements. The audible alarm sounds when this
indicator lights .
Note: A lit Low Pressure fault indicator condition disables the controller outputs and heaters but
still allows the pump to continue circulating fluid to prevent damage to the heater
elements.
Auto Heat/Cool
When lit, the controller monitors the system and controls the process temperature.
Manual Cool
When lit, the controller is disabled and the cooling solenoid is open to allow maximum cooling.
Note: If neither
Manual Cool
or
Auto Heat/Cool
is on, the unit is in Standby mode. While in
Standby mode, the pump continues to run, the immersion heater will not energize, and the
cooling solenoid, if so equipped, will not open.
Low Level (optional)
When lit, this advisory indicator warns of low fluid level in the reservoir tank .
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Page 33