Carrier WeatherExpert 48N2 Controls, Start-Up, Operation, Service, And Troubleshooting page 131

measured pressure (Pressures  AIR.P  BP) is above the limit
for 5 minutes, then the alert will occur.
T314 (IAQ Above Limit)
If the unit is configured to use a CO
puts  AIR.Q  IAQ) is above the configurable IAQ High
Alert Limit (Configuration  IAQ  ALLM  IAQ.H) for 5
minutes, then the alert will occur. The unit will continue to run
and the alert will automatically reset.
T316 (OAT Below Limit
If the outside-air temperature measured by the OAT thermistor
(Temperatures  AIR.T  OAT) is below the configurable OAT
Low Alert Limit (Configuration  IAQ  ALLM  OAT.L) for 5
minutes, then the alert will be broadcast.
T317 (OAT Above Limit
If the outside-air temperature measured by the OAT thermistor
(Temperatures  AIR.T  OAT) is above the configurable OAT
High Alert Limit (Configuration  IAQ  ALLM  OAT.H) for
5 minutes, then the alert will be broadcast.
T318 (Static Pressure (SP) Not Holding Setpoint)
If the static pressure (Pressures  AIR.P  SP) is outside the
range Configuration  SP  SP.SP ± Configuration  PROG 
PG.SP for 5 minutes and the Prognostics SP Enable is enabled
Configuration  PROG  P.SPE, this alert will be logged. Re-
covery is automatic. The reason for the alert is that the static pres-
sure set point is not being held by the supply fan.
T319 (Building Pressure (BP) Not Holding Setpoint)
If the building pressure (Pressures  AIR.P  BP) is outside
the range Configuration  BP  BP.SP ± Configuration 
PROG  PG.BP for 5 minutes and the Prognostics BP Enable
is enabled, Configuration  PROG  P.BPE this alert will be
logged. Recovery is automatic. The reason for the alert is that
the building pressure is not being held by the power exhaust or
return fan.
T331 (SH_A1 Flooding Detected)
T332 (SH_A2 Flooding Detected)
T333 (SH_B1 Flooding Detected)
T334 (SH_B2 Flooding Detected
If EN.SC=YES, after logging the flooding alert, the circuit
shall be marked as failed, forcing a circuit shutdown and recal-
ibration of the shutdown circuit EXVs. The alert shall be auto-
matically cleared FL.TM after being set. After clearing the
alert, the circuit shall be immediately marked as usable. Shut-
down due to flooding will not shut down both circuits at same
time due to flooding alert. Second circuit will wait for alert to
automatically clear on first circuit before shutting down.
If an excessive number of flooding detected alerts are seen in
the unit alarm history, it may be necessary to lower the EXV
minimum position (EX.MN) from its default setting of 20%.
Note that lowering this setting could cause an increase in the
number of high head pressure alerts. In no case should the set-
ting be below 10%.
T335 (Excess Outdoor Air)
When the control detects a stuck or jammed actuator, it shall
compare the stuck position to the command position to log ad-
ditional alerts. If the stuck position > commanded position, the
alert is set.
A400 (Hydronic Freeze Stat Trip)
If the freezestat for the hydronic coil trips, the unit goes into
emergency mode and does not allow cooling or heating. The
economizer goes to 0% open. Supply fan operation is enabled.
Recovery is automatic when the switch goes off.
A404 (Fire Shut Down Emergency Mode [fire-smoke])
If the fire shutdown input is energized (fire shutdown is in effect),
or if 2 fire smoke modes are incorrectly energized at the same
time, a Fire Shutdown mode will occur. This is an emergency
sensor and the level (In-
2
mode requiring the complete shutdown of the unit. Recovery is
automatic when the inputs are no longer on.
A405 (Evacuation Emergency Mode
If the evacuation input on the CEM is energized, an evacuation
mode occurs which flags an alarm. This mode attempts to low-
er the pressure of the space to prevent smoke from moving into
another space. This is the reverse of the Pressurization Mode.
Closing the economizer, opening the return-air damper, turning
on the power exhaust, and shutting down the indoor fan will
decrease pressure in the space. Recovery is automatic when the
input is no longer on.
A406 (Pressurization Emergency Mode)
If the pressurization input on the CEM is energized, a pressuriza-
tion mode occurs which flags an alarm. This mode attempts to
raise the pressure of a space to prevent smoke infiltration from
another space. The space with smoke should be in an Evacuation
Mode attempting to lower its pressure. Opening the economizer,
closing the return-air damper, shutting down power exhaust, and
turning the indoor fan on will increase pressure in the space. Re-
covery is automatic when the input is no longer on.
A407 (Smoke Purge Emergency Mode)
If the smoke purge input on the CEM is energized, a smoke
purge mode occurs which flags an alarm. This mode attempts
to draw out smoke from the space after the emergency condi-
tion. Opening the economizer, closing the return-air damper,
and turning on both the power exhaust and indoor fan will
evacuate smoke and bring in fresh air. Recovery is automatic
when the input is no longer on.
T408 (Dirty Main Air Filter)
If no dirty filter switch is installed, the switch will read "clean
filter" all the time. Therefore the dirty filter routine runs con-
tinuously and diagnoses the input. Because of the different pos-
sible times it takes to generate static pressure, this routine waits
2 minutes after the fan starts before the dirty filter switch is
monitored. If the dirty filter switch reads "dirty filter" for 2
continuous minutes, an alert is generated. No system action is
taken. This is a reminder that it is time to change the filters in
the unit. Recovery from this alert is through a clearing of all
alarms (manual) or after the dirty filter switch reads clean for
30 continuous seconds (automatic).
T409 (Supply Fan Commanded On, Sensed Off Failure)
T409 (Supply Fan Commanded Off, Sensed On Failure)
A409 (Supply Fan Commanded On, Sensed Off Failure)
A409 (Supply Fan Commanded Off, Sensed On Failure)
Both the alert and the alarm refer to the same failure. The only
difference between the alarm and alert is that in the case where
the supply fan status configuration to shut down the unit is set
to YES (Configuration  UNIT  SFS.S), the alarm will be
generated AND the unit will be shut down. It is possible to
configure Configuration  UNIT  SFS.M to either a switch
or to monitor a 0.2-in. wg rise in duct pressure if the unit is
VAV with duct pressure control.
The timings for failure for both are the same and are illustrated
in the following table:
UNIT TYPE/MODE
CV (no gas heat)
CV (gas heat)
VAV (no gas heat)
VAV (gas heat)
Recovery is manual. Reason for failure may be a broken fan
belt, failed fan relay or failed supply fan status switch.
A410 (Supply Fan VFD Fault)
The MBB has received a fault status from the supply fan VFD.
The unit will be shut down, and a manual reset is required. The
131
MINIMUM ON MINIMUM OFF
TIME WAIT TIME WAIT
30 seconds 1 minute
2 minutes 4 minutes
1 minute 1 minute
3 minutes 4 minutes