Carrier 48HC 04-28 Controls, Start-Up, Operation And Troubleshooting page 44

be necessary. Cycling power to the control and reconfiguring the
time and date should be tried before board replacement.
Alarm Code A154 — Serial EEPROM Hardware Failure
The unit will completely shut down. The serial EEPROM chip
on the MBB which stores the unit's configuration is not re-
sponding. Recovery is automatic, but MBB board replacement
may be necessary. Cycling the power to the control should be
tried before board replacement.
Alarm Code T155 — Serial EEPROM Storage Failure Error
Configuration data in the serial EEPROM chip can not be veri-
fied. The unit will run to last know good values or defaults, and
therefore operating errors may occur. Recovery is automatic
but MBB board replacement may be necessary. Cycling power
to the control and reconfiguring the control points should be
tried before board replacement.
Alarm Code A156 — Critical Serial EEPROM Storage Fail
Error
The unit will completely shut down. Critical configuration data
in the serial EEPROM chip can not be verified. Recovery is au-
tomatic but MBB board replacement may be necessary. Cy-
cling power to the control and reconfiguring the critical control
points should be tried before board replacement. Check the
configurations for the following critical points:
 
Configuration COOL N.CIR (Number of Circuits)
 
Configuration HMZR REHT (Humidi-MiZer Equipped)
Alarm Code A157 — A/D Hardware Failure
The unit will completely shut down. The analog to digital con-
version chip on the MBB has failed. Recovery is automatic but
MBB board replacement may be necessary. Cycling power to
the control should be tried before board replacement.
Alarm Codes A163 and A164 — Circuit Down due to Failure
Alarm codes A163 and A164 are for circuits A and B respec-
tively. These alarms have "Service Test" text that will be dis-
played if the alarm occurred during service test. These alarms
occur when a circuit has 3 strikes. Use the scrolling marquee
display to reset the alarm. Investigate the alarm that caused the
strikes to occur.
Alert Code T173 — Loss of Communication with the Energy
Management Module
This alert occurs when the MBB cannot communicate with the
EMM. These units do not currently support any operation with
the EMM. This alert is caused by an internal force to look for
the EMM board. When this happens, reload software on the
MBB and do not restore configurations, the factory configura-
tions must be used at first. Replace the MBB if alert continues.
Alert Code T175 — Loss of communication with VFD
This alert occurs when the Indoor Fan Type (Configuration

I.FAN FTYP) is set to 1 and the MBB cannot communicate
with the VFD. The control will shutdown the unit and prevent
normal operation. This alert will automatically reset when
communication is established again. This alert is usually
caused by a wiring problem or a incorrect configuration in the
VFD or the MBB.
Alert Code T179 — Loss of Communication with the Econo-
mizer Control Board
This alert occurs when the MBB cannot communicate with the
ECB. Economizer operation will be disabled. This is usually
caused by a wiring problem. If a relative humidity sensor is in-
stalled and configured but there is not an ECB installed on the
unit, this alert will be generated (the ECB is required for RH
sensor operation). Investigate using the Low Voltage Schemat-
ic, check that the ECB address is correct, and verify the resis-
tance between pins on the LEN connections.
Alert Code T180 — Loss of Communication with the Econo-
mizer Actuator
This alert occurs when the ECB cannot communicate with the
Belimo Actuator. If the analog signal is connected properly, the
economizer can still be controlled through it. This is usually
caused by a wiring problem, actuator failure, or the wrong ac-
tuator. Investigate using the Low Voltage Schematic. Make
sure the actuator is a MFT communication actuator and verify
the feedback signal from the actuator is correct.
Alert Code T181 — Loss of communication with Outside Air
Unit
This alert occurs when the Outdoor Air Unit Type (Configura-
 
tion OAU OA.TY) is not set to 0 and the OAU Operating
Mode (Run Status
cated in the past 3 minutes. The control will reset all OAU da-
ta. This alert will automatically reset when communication is
established again. This alert is usually caused by a wiring prob-
lem or a problem with the OAU communication.
Alarm Code A200 — Linkage Timeout - Comm Failure
This alarm occurs when the MBB fails to communicate with a
Linkage device. This only occurs when the MBB has previous-
ly communicated with a Linkage device since last power cycle.
If a back up sensor was not installed the T074 alert will occur
shortly after this one. Reset power to the unit and verify Link-
age is communicating.
Alarm Code A404 — Fire Shutdown
This alarm occurs when the shutdown input is either open or
closed depending upon its configuration. This alarm is usually
caused by an auxiliary device that is trying to shut down the
unit, e.g., smoke detector. The configuration for this switch in-
put can be found at variable Configuration
Verify that the configuration is set correct, verify the wiring
and auxiliary device. This alarm resets automatically.
Alert Code T408 — Dirty Air Filter
This alert occurs when the Filter Status switch senses a
plugged filter for 120 continuous seconds after the indoor fan
has been running for 10 seconds. Because the Dirty Air Filter
switch can be configured normally opened or closed, the
switch might be open or closed. The configuration for this
switch input can
 
tion UNIT FL.SW. Verify that the configuration is set cor-
rect, verify the wiring and filter status switch. The hose should
be connected to the low side of the switch. This alert resets au-
tomatically.
Alert Code T409
There are 2 different texts for this alert code. Pressing enter and
esc on the marquee or navigator to expand the T409 alert will
show you one of the below alerts. Make sure the expanded text

is read correctly before troubleshooting.
• Fan Status Switch On, Fan Contactor Off
This alarm occurs when the fan status switch has sensed that
the indoor fan has been on for 10 seconds and the indoor fan
feedback has determined that the indoor fan should be off. Be-
cause the Fan Status switch can be configured normally opened
or closed, the switch might be open or closed. The configura-
tion for this switch input can be found at Configura-
 
tion UNIT FN.SW. Verify that the configuration is set cor-
rectly. Verify the wiring and fan status switch. The hose should
be connected to the high side of the switch. If the IDF is con-
figured to shut down the unit when this alarm occurs (Configu-
 
ration I.FAN IDF.F = YES), then this alarm can only be
reset manually and the unit is shut down. If the IDF is not con-
figured to shut the unit down when this alarm occurs (IDF.F =
NO), then this alarm resets automatically and no specific con-
trol action is taken.
• Fan Status Switch Off, Fan Contactor On
44
 
OAU OA.OP) has not been communi-

be found at variable

UNIT FS.SW.
Configura-