Fan overload - Johnson Controls - LIT-12011950 - Building automation software - Smart Equipment Controller - 5.0

Smart Equipment Controls Sequence of Operation Technical Bulletin

Johnson Controls
Product name
Smart Equipment Controller
Document type
Technical Bulletin
Document number
Revision date
Product status

Setpoints and related data

The setpoints and related data include the following items:

  • Unit locked out supply fan overload (FanOvrload-LO)
  • Reset lockouts (ResetLO)


The input for fan overload is contact closure from fan overload (FanOvrload).


The output for fan overload is the output relay for fan, compressors, and condenser fans.


Any time the fan overload contact opens for more than 5 seconds, the UCB shuts down the fan, all of the compressors, and the condenser fan outputs. If the contact closes, the UCB clears the alarm. If the contact does not close within 15 minutes the UCB flags an alarm, turns on the X line, and displays the appropriate alarm code on the LCD.

If voltage returns, the UCB logs the first incident and tracks the runtime. If the fan overload contact opens three times within 2 hours of run time, the UCB shuts down. It locks out the compressors, turns off the indoor fan, turns off the outdoor fan, turns on the X line, and displays the appropriate LCD alarm.

If the UCB senses W1 and a fan overload fault, it does not lock out the fan. As long as there is a W1 present, the UCB retries the fan each time the switch closes.

Note: This alarm is reset only through a shut down, or through the ResetLO command from the LCD.