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Electronic Theatre Controls Inc

CEM Classic says Airflow Problems or No Airflow


All loads connected to a Sensor Classic rack will either be stuck off or will fade off and on at the same time. CEM reports "Airflow Problems" or "No Airflow" on the display.


The Sensor rack may not be receiving enough airflow through the rack.

  • Check to make sure the fan is spinning and air is blowing from the top of the rack. 
  • Open the rack door, take out the filters, and make sure that the filters are clean. If the filters are dirty, they can be blown out or washed. Be sure to dry the filters before installing.
  • Power off the rack using proper lockout/tagout procedures, and check:
    • That all holes and conduits are sealed. This includes holes made for inter-rack connections for bussed rack systems. Great Stuff and fiche paper work well to seal the rack. 
    • That the load wiring connected to the lugs on the right side of the rack is neatly dressed, wire tied, and pushed all the way to the rear of the enclosure. 
    • That there is not excessive dirt or dust inside the rack which may impede airflow. The inside of the modules and enclosure may be cleaned using compressed air and a vacuum.
  • Check to make sure that there are no major air currents that are blowing across or at the front of the rack. This creates a vacuum at the entry point of the rack.
    • Note that for proper airflow and dust management, the rack door must be closed during normal operation. 

The airflow sensor on the CEM may be failing or have already failed.

  • When this component fails, you get airflow errors and flickering despite good airflow.
  • Make sure you have already checked all of the above items before determining it to be an airflow sensor issue.
  • If the sensor has failed, you will need to send the CEM in for repair. Contact ETC Technical Services.
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