Manual 2100-665A
Page
27 of 51
ALARMS
Alarm Adjustment
Acknowledging/Clearing Alarms
Alarm conditions activate a red LED indicator that
backlights the ALARM function key. As an option, an
alarm condition may also be enunciated by an audible
alarm signal. An alarm is acknowledged by pressing the
ALARM key. This calls up alarm display screen(s) that
provide a text message detailing the alarm condition(s).
After an alarm condition is corrected, the alarm can be
cleared by pressing the ALARM key for 3 seconds.
Mixed Air Alarm
The mixed air alarm is used to indicate proper
operation of the economizer. An alarm will be generated
when the mixed air temperature is above or below two
independant setpoints.
This alarm can be adjusted by changing the alarm
setpoints and/or delay. The differential low references
the economizer control setpoint. For example, if the
economizer setpoint is 55°F (as shown in Figure 2.15
on page 32) and the differential is set to 10, the lower
limit for the mixed air alarm would be 45°F. The high
differential references the outdoor air temperature
setpoint that enables the economizer. For example, if
the outdoor air temperature setpoint for economizer
enable is set to 65°F and the high differential is set
to 5 (as shown in Figure 2.13 on page 31), the alarm
would actuate at 70°F. The alarm also has a delay to
help reduce nuisance alarms. With the delay set to
10 seconds, either the high mixed air or low mixed air
alarm will need to be active for 10 seconds before an
alarm will be generated.
To adjust these values:
1. Press MENU key to go to the Main Menu screen.
2. Press UP or DOWN keys and ENTER key to enter
USER password 2000.
3. Press UP or DOWN keys to scroll to
Sys Config
;
press ENTER key.
4. Press UP or DOWN keys to scroll to
Alarm Config
(A7)
; press ENTER key.
5. Press ENTER key to scroll to desired value
Diff Lo
,
Diff Hi
or
Del
(see Figure 2.6).
6. Press UP or DOWN keys to adjust value.
7. Press ENTER key to save.
Refrigerant Low Pressure
When the low pressure switch indicates a low pressure
condition and there is an active call for cooling, the
controller will generate an alarm (after a delay). The
delay used by the low pressure alarm is determined
by the outdoor air temperature (OAT on display). If the
outdoor air temperature is below 55°F, the delay is 180
seconds (Del on display). If the outdoor temperature
is above 55°F, the delay is 120 seconds (LDel on
display). The unit will also have an address-based delay
that will affect start up time. The default is 5 seconds
multiplied by unit adress. Additionally, if the outdoor
temperature sensor is not used, the delay is set to 180
seconds. The controller will try to run the refrigeration
system two times before the alarm will lock the
compressor out.
If 15 minutes (Two Count Del value on display) passes
before the second attempt, the number of tries will be
reset.
To adjust these values:
1. Press MENU key to go to the Main Menu screen.
2. Press UP or DOWN keys and ENTER key to enter
USER password 2000.
3. Press UP or DOWN keys to scroll to
Sys Config
;
press ENTER key.
4. Press UP or DOWN keys to scroll to
Alarm Config
(A7)
; press ENTER key.
5. Press ENTER key to scroll to desired value
OAT
,
Diff
,
Del
,
LDel
or
Two Count Del
(see Figure 2.6).
6. Press UP or DOWN keys to adjust value.
7. Press ENTER key to save.
Refrigerant High Pressure
When the wall unit receives a signal from the
compressor control module (CCM) indicating a high
pressure event, the wall unit will generate an alarm.
FIGURE 2.6
Adjusting Mixed Air Alarm Values
