The Two Compressor Run alarm occurs whenever the two units are required to use mechanical cooling at the same time. This alarm is an early warning that one of the units may have reduced cooling capacity.


Possible Cause
Component to Check
Recommended Action
Reduced sensible capacity of lead unit
Air filter, condenser, refrigerant charge
Replace filter, clean condenser, and recharge refrigerant.
One unit unable to use mechanical cooling
Use step test to verify compressor operation on both units
Refer to A07, High Temp Alarm to troubleshoot compressor
Shelter heat load exceeds rated sensible capacity of an individual unit
Shelter heat load, unit sensible capacity
Add/upgrade unit. Reduce heat load by shutting down unused equipment.
Exceptionally high outdoor temperature (>>95˚F)
Expected behavior
Ensure site is not “leaky” and allowing hot air through holes in the shelter
Improper lag unit turn on point
F38 under L05 Menu
Recommended at least 5°F for F38