Low ambient operation - 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:

  • Cooling OAT cutout enable (ClgOATCutout-En) Yes
  • Cooling OAT cutout (ClgOATCutout)
  • Low Ambient Enabled (LoAmb-En)
  • Low ambient 10 on 5 off setpoint (LowAmb10On5OffSp)


If cooling OAT cutout enable is set to yes, the compressor operation is not permitted if the OAT is less than the cooling OAT cutout.

If cooling OAT cutout enable is set to no, the compressors cycle 10 minutes on and 5 minutes off if the OAT is less than the low ambient 10 on 5 off setpoint (LowAmb10On5OffSp) setpoint.

If a compressor is in the 10-minute on cycle and the evaporator temperature (EC1 through EC4) drops below 26°F, the compressor output de-energizes and the 5-minute ASCD starts. After the 5-minute ASCD expires, the compressor output is permitted.

Any time the compressor output de-energizes due to the evaporator coil temperature protection, it does not count toward a hard compressor lockout.