Carrier WeatherExpert 48N2 Controls, Start-Up, Operation, Service, And Troubleshooting page 132

VFD keypad will indicate which fault has occurred. Reset can be
done at the unit control (Alarms  R.CUR) or the VFD keypad.
T411 (Exhaust Fan VFD Fault)
The MBB has received a fault status from the exhaust fan
VFD. Building pressure control will be stopped and a manual
reset is required. The VFD keypad will indicate which fault has
occurred. Reset can be
(Alarms  R.CUR) or the VFD keypad.
T412 (Dirty Post Air Filter)
If no dirty post filter switch is installed, the switch will read
"clean filter" all the time. Therefore the dirty post filter routine
runs continuously and diagnoses the input. Because of the dif-
ferent possible times it takes to generate static pressure, this
routine waits 2 minutes after the fan starts before the dirty post
filter switch is monitored. If the dirty post 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 post filters in the unit. Recovery from this alert is
through a clearing of all alarms (manual) or after the dirty post
filter switch reads clean for 30 continuous seconds (automatic).
A413 (Air Pressure Safety Switch Trip)
If the air pressure switch trips, the unit will be instructed to
shut down immediately. Manual reset of the switch is required.
Software reset is automatic when switch has been reset. Possi-
ble causes are blocked outlets on the building discharge duct,
or the duct pressure control system (i.e., duct pressure trans-
ducer, VFD, supply fan) has failed.
T414 (Damper Not Modulating)
This alert occurs when the supply air temperature does not
change as expected when the damper is moved. Check to deter-
mine if the damper is no longer mechanically connected to the
actuator. Reset is manual.
P415 (Main Air Filter Notification – Change Soon)
If the unit is configured for Dirty Filter Notification via Sched-
ule, Configuration  FLTC  MFL.S = 2 (Schedule), this alert
will occur when the life remaining in the filter is below the re-
minder level MF.RM.
If the unit is configured for Dirty Filter Notification via Predic-
tive Life L, Configuration  FLTC  MFL.S = 4 (Predictive
Life Calculate and Learn) or via Predictive Life Configura-
tion  FLTC  MFL.S = 5 (Predictive Life Calculate Only),
this alert will occur when the life remaining in the filter is be-
low the notification level F.NOT.
P416 (Post Air Filter Notification – Change Soon)
If the unit is configured for Dirty Filter Notification via Sched-
ule, Configuration  FLTC  PFL.S = 2 (Schedule), this alert
will occur when the life remaining in the filter is below the re-
minder level PF.RM.
If the unit is configured for Dirty Filter Notification via Predic-
tive Life L, Configuration  FLTC  PFL.S = 4 (Predictive
Life Calculate and Learn) or via Predictive Life Configura-
tion  FLTC  PFL.S = 5 (Predictive Life Calculate Only),
this alert will occur when the life remaining in the filter is be-
low the notification level F.NOT.
T421 (Thermostat Y2 Input On without Y1 On)
If Y2 is on and Y1 is off, then this alert condition is initiated.
The control continues as if both Y1 and Y2 were requested.
Alert recovery will not occur until Y1 is seen. This handles
some conditions of an incorrectly wired thermostat and may
prevent multiple alerts and recoveries from clogging the alarm
histories.
T422 (Thermostat W2 Input On without W1 On)
If W2 is on and W1 is off, then this alert condition is initiated.
The control continues as if both W1 and W2 were requested.
Alert recovery will not occur until W1 is seen. This handles
some conditions of an incorrectly wired thermostat and may
done at the unit control
prevent multiple alerts and recoveries from clogging the alarm
histories.
T423 (Thermostat Y and W Inputs On)
Simultaneous calls for heating and cooling are illegal and will
be alarmed. Cooling and heating will be locked out. Recovery
is automatic when the condition no longer exists.
T424 (Thermostat G Input Off On a Cooling Call)
If G is off and there is a cooling request (Y1 or Y2), then it is
possible the G connection has not been made to the unit termi-
nal block. An alert is initiated for this condition as continuous
fan operation and manual fan control may not be possible.
Cooling is started, if allowed, and the fan is turned on. The
controls do not diagnose the fan if a heat request (W1 or W2) is
in progress.
T430 (Plenum Pressure Safety Switch Trip)
A430 (Plenum Pressure Safety Switch Trip)
If the unit is configured for fan tracking and the plenum pressure
switch trips, the unit will be instructed to shut down immediate-
ly. The first 2 times the switch trips, the unit will automatically
start up and clear the alert 3 minutes after the switch recovers.
The third time the switch trips, the unit shuts down and calls out
the alarm. Manual reset of the switch (located in the auxiliary
control panel) is required. Software reset is automatic when
switch has been reset. Possible causes are blocked exhaust or re-
turn dampers causing high pressure at the plenum fan.
T431 (PE Motor Starter Protector Tripped)
A432 (PE Motor Starter Protector Lockout)
If the unit is configured for VFD power exhaust (BP.CF=3),
the unit monitors the status of the 2 power exhaust motor start-
er protectors in the power leads between the PE VFD and the
PE Motors. If either one of the motor starter protectors trip, the
alert T431 will be broadcast. The Building Pressure routine
will continue to operate but with only one power exhaust fan.
Depending on the operating conditions, the unit may not be
able to maintain the desired building pressure.
If both of the motor starter protectors trip, the alert A432 will be
broadcast and Building Pressure Control routine will shut down.
Possible causes are overloading of the power exhaust motor(s)
or wrong setting for the motor starter protector(s). Software reset
is automatic when the switch(es) have been reset.
A433 (3-Phase Power Failure)
If the unit is configured for power monitoring (Configura-
tion  UNIT  PW.MN = YES), if the power monitor input
trips (Inputs  GEN.I  PWR.F = ALRM), the unit will be in-
structed to shut down immediately. Software reset is automatic
when input has been reset. Possible causes are under/over volt-
age, phase loss, or phase unbalance.
T500 (Current Sensor Board Failure - A1)
T501 (Current Sensor Board Failure - A2)
T502 (Current Sensor Board Failure - B1)
T503 (Current Sensor Board Failure - B2)
If the current sensor board malfunctions or is not properly con-
nected to its assigned digital input, an alert will be generated. It
takes 2 to 4 seconds to log the alert. If the alert is logged, it
stays active for a minimum of 15 seconds to provide the appli-
cation a reasonable time to catch the failure. Compressors will
not be inhibited by this failure. Recovery is automatic. Reason
for failure may be a faulty current sensor board, incorrect wir-
ing, or a damaged input on the MBB control board.
T504 (Current Sensor Board Failure - A3)
T505 (Current Sensor Board Failure - B3)
T506 (Current Sensor Board Failure - A4)
T507 (Current Sensor Board Failure - B4)
If the current sensor board malfunctions or is not properly con-
nected to its assigned digital input, an alert will be generated. It
takes 2 to 4 seconds to log the alert. If the alert is logged, it stays
active for a minimum of 15 seconds to provide the application a
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