Instruction manual

OM 751-4 20 www.DaikinApplied.com
desCrIptIon of operatIon
Mech State (State 2)
The Mech state is a “normal” state during Cool mode. The Mech state typically is active
in the Cool mode when primary cooling (economizer) is not available and secondary
cooling (compressor) is available.
When the Mech state becomes active, the UVC will (within State) continually calcu-
late the DATS (“Discharge Air Temperature Control” on page 31) required to maintain
the effective cooling set point (see "Space Temperature Set Points" on page 29). The
calculated DATS will not be allowed to go below MCLL. If cooling is not required while
in the Mech state, the UVC can “idle” in the Mech state until cooling is required or until
there is a call to switch to another mode or state.
The CO
2
demand controlled ventilation function (optional) is active (see “CO
2
De-
mand Controlled Ventilation (optional)” on page 36), and the OA damper is adjusted as
needed to maintain the CO
2
set point.
Figure 13: Mech state operation (occupied mode and auto fan)
Cant Cool State (State 12)
The Cant Cool state is a “non-normal” state during Cool mode. The Cant Cool state
typically becomes active when both primary (economizer) and secondary (compres-
sor) cooling are not available (or they are disabled) or when an IAT, DAT or OAT sensor
failure occurs.
When the Cant Cool state becomes active, no cooling is available.