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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 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 (IGV or VFD).
The timings for failure for both are the same and are illustrated
in the following table:
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
VFD keypad will indicate which fault has occurred. Reset can be
done at the unit control (Alarms
R.CUR) or the VFD keypad.
A411 (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 done at the unit control (Alarms
R.CUR) or the VFD keypad.
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 automatic on economizers with only one actua-
tor. Manual reset is required on economizers with two actuators.
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
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 (Power Exhaust Motor Starter Protector Trip)
A432 (Power Exhaust Motor Starter Protector Lock)
If the unit is configured for VFD power exhaust (BP.CF=3),
the unit monitors the status of the (2) Power Exhaust Motor
Starter 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 ex-
haust 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 the Building Pressure Control routine will
shut down. Possible causes are overloading of the Power Ex-
haust Motor(s) or wrong setting for the Motor Starter Protec-
tor(s). Software reset is automatic when the switch(es) have
been reset.
T500 (Current Sensor Board Failure - A1)
T501 (Current Sensor Board Failure - A2)
T502 (Current Sensor Board Failure - B1)
T503 (Current Sensor Board Failure - B2)
T504 (Current Sensor Board Failure - A3)
T505 (Current Sensor Board Failure - B3)
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
UNIT TYPE/MODE MINIMUM
ON TIME WAIT
MINIMUM
OFF TIME WAIT
CV (no gas heat) 30 seconds 1 minute
CV (gas heat) 2 minutes 4 minutes
VAV (no gas heat) 1 minute 1 minute
VAV (gas heat) 3 minutes 4 minutes
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