Unit Events; Circuit Events - Daikin AGZ 025D Operating & Maintenance Manual

Unit Events

Unit Power Restore
Trigger: Unit controller is powered up.
Action Taken: none.
Reset: none.

Circuit Events

Low Evaporator Pressure - Hold
Trigger:
This event is triggered if all of the following are true:

circuit state = Run

evaporator pressure <= Low Evaporator Pressure - Hold set point

circuit is not currently in a low OAT start

it has been at least 30 seconds since a compressor has started on the circuit.
Action Taken: Inhibit starting of additional compressors on the circuit.
Reset: While still running, the event will be reset if evaporator pressure > Low Evaporator Pressure
Hold SP + 90 KPA(13 PSI). The event is also reset if the circuit is no longer in the run state.
Low Evaporator Pressure - Unload
Trigger:
This event is triggered if all of the following are true:

circuit state = Run

more than one compressor is running on the circuit

evaporator pressure <= Low Evaporator Pressure - Unload set point for a time greater than
half of the current freezestat time

circuit is not currently in a low OAT start

it has been at least 30 seconds since a compressor has started on the circuit
On units equipped with 6 compressors, electronic expansion valves, and 10 or more fans, when each
compressors starts, there should be a 2 minute window during which the evaporator pressure must
drop an additional 27 KPA (3.9 PSI) to trigger the alarm. After this 2 minute window, the trigger point
should return to normal.
Action Taken: Stage off one compressor on the circuit every 10 seconds while evaporator pressure is
less than the unload set point, except the last one.
Reset: While still running, the event will be reset if evaporator pressure > Low Evaporator Pressure
Hold SP + 90 KPA(13 PSI). The event is also reset if the circuit is no longer in the run state.
High Condenser Pressure - Unload
Trigger:
This event is triggered if all of the following are true:

circuit state = Run

more than one compressor is running on the circuit

condenser pressure > High Condenser Pressure – Unload set point
42 AGZ 025D through 190D OMM 1166-1