Unit installation

30 ACZ 010A through 039A IOMM ACZ1-2
Events (Limit Alarms)
The following events limit the operation of the unit in some way as described in the Action
Taken column. These alarms are auto-clearing based on reaching the conditions in the reset
column.
Table 12, Event (Limit) Alarms
Description Occurs When: Action Taken Reset
Condenser Pressure
High Unload
Pressure > High Condenser Stage
Down setpoint
Shutoff
Stage #2
Condenser Press drops
below (SP – 100psi)
Evaporator Pressure
Low – Hold
Pressure < Low Evap Pressure–Hold
setpoint AND one compessor is running
Hold @
Stage 1
Evap Press rises above
(SP + 8psi)
Evaporator Pressure
Low – Unload
Pressure < Low Evap Pressure–Unload
setpoint
Shutoff
Stage 2
Evap Press rises above
(SP + 10 psi)
Failed Pumpdown Unit is pumping down for 60 seconds
Shutoff
Compressors
N/A
Active Alarm List
When an alarm occurs, it appears in the active alarm list. The active alarm list holds a
record of all active alarms, which includes the date and time each occurred. The active
alarms can be cleared by pressing the Edit key when the end of the list has been reached by
scrolling.
Active alarms may be cleared without a password being active. The condition that caused
the alarm must be corrected prior to clearing the alarm to avoid filling the buffer with
duplicate entries and also to avoid repeated trips from the same cause.
Alarm Logging
A separate alarm log stores the last 25 alarms to occur. When an alarm occurs, it is put into
the first slot in the alarm log and all others are moved down one, dropping the last alarm.
In the alarm log, the date and time the alarm occurred are stored, as well as a list of other
parameters. These parameters include compressor states, evaporator pressure, condenser
pressure, number of fans on, and OAT.
Event Logging
An event log similar to the alarm log holds the last 25 events to occur. When an event
occurs, it is put into the first slot in the event log and all other entries are moved down one,
dropping the last event. Each entry in the event log includes an event description as well as
the time and date of the occurrence. No additional parameters are logged for events. A
password must be active to view the event log.
Control Functions and Definitions
Refrigerant Saturated Temperature
Methods for calculating saturated refrigerant temperature differ with each refrigerant as
explained below.
R22 Saturated Temperature
Evaporator saturated temperature and condenser saturated temperature are calculated from
the pressures for each circuit. The pressure is fit to a curve made up of 13 straight line
segments. The points used to define these segments are as follows: