Carrier 50HCQ04---12 - Manual (Page 24)

24
Alarms
Alarms are provided to indicate a possible problem with
the controller or unit. Alarms can be checked through a
network and/or the local access device. All alarms are
listed in Table 4 with name, object name, action taken by
control, reset method, and possible cause. Some alarms
can occur based on specific configurations.
Safety Chain Alarm
This alarm occurs immediately if the supply-fan internal
overload trips or if an electric-heat limit switch trips. The
Unit Status will be Shutdown and the System Mode will
be Disable. All unit operations stop immediately and will
not restart until the alarm automatically clears. There are
no configurations for this alarm; it is all based on internal
wiring. This alarm will not occur if Fire Shutdown Alarm
is active. Normal operation resumes when the safety
chain circuit is complete.
Fire Shutdown Alarm
This alarm occurs immediately when the smoke detector
senses smoke. The Unit Status will be Shutdown and the
System Mode will be Disable. All unit operations stop
immediately and will not restart until the alarm
automatically clears. If there is not a smoke detector
installed or the smoke detector did not trip, check input
configurations. NOTE: The default function for input 5 is
a normally open Fire Shutdown input.
Supply Fan Failure
This alarm occurs when the indoor fan is being command
on and the fan status switch feedback is showing the fan
off. This will end current operating mode and disable unit
operation. This alarm requires a fan status switch to be
configured on one of the inputs.
Supply Fan in Hand
This alarm occurs when the indoor fan is being
commanded off and the fan status switch feedback is
showing the fan is on. This will prevent any operating
mode and disable unit operation. This alarm requires a
fan status switch to be configured on one of the inputs.
Compressor Safety
This alarm indicates the base unit’s compressor safety
circuit is energized. Cooling, heating, and supply fan
outputs are not interrupted except when the RTU-OPEN is
configured for Heat Pump. Normal operation resumes
when the compressor safety circuit is de-energized. If the
Heat Pump is in the heating mode, it will automatically
replace the compressor stage(s) with the equivalent
number of auxiliary heat stages, as available.
For Heat Pump’s with O/B, when configured for two
stages of aux heat and two compressors, Compressor 1 is
replaced by Aux Heat Stage 1 and Compressor 2 is
replaced by Aux Heat Stage 2. The compressor output
stays on when the safety alarm is present. For cooling, the
alarm indicates the compressors are down.
Space Temp Sensor
This alarm occurs if the space sensor wired to the
RTU-OPEN is disconnected or shorted for more than 10
seconds. When this occurs the Unit Status will be
Shutdown and the System Mode will be Run. Sensor,
sensor connections, wiring, board connection, and
configurations should be checked for faults or errors.
Alarm will reset automatically when cause is fixed.
Supply Air Temp Sensor
This alarm occurs immediately when the supply air
temperature sensor wired to the RTU-OPEN is
disconnected or shorted. When this occurs the Unit Status
will be Shutdown and the System Mode will be Run.
Sensor, sensor connections, wiring, board connection, and
configurations should be checked for faults or errors.
Alarm will reset automatically when cause is fixed.
Outdoor Air Temp Sensor Alarm
This alarm indicates a shorted or open circuit in the OAT
input. Cooling, heating, and supply fan operation
continues. OAT lockouts will not operate while the sensor
is in alarm. Economizer cooling and optimal start
functions are disabled. Normal operation resumes when
the controller detects a valid sensor.
Space Relative Humidity Sensor
This alarm indicates the mA input at the associated
channel falls below 3.5 mA or rises above 21 mA.
Cooling, heating, and supply fan operation continues,
however, the controller’s Humidi-MiZert binary output
is disabled until the fault condition is corrected.
IAQ Sensor
This alarm indicates the mA input at the associated
channel falls below 3.5 mA or rises above 21 mA.
Cooling, heating, and supply fan operation continues.
However, the controller’s IAQ control function is disabled
until the fault condition is corrected.
OAQ Sensor
This alarm indicates the mA input at the associated
channel falls below 3.5 mA or rises above 21 mA.
Cooling, heating, and supply fan operation continues.
However, the controller’s IAQ control function uses
400ppm as the fixed outdoor air CO2 level until the fault
condition is corrected.
Space Temperature
When Occupied, a Low Space Temperature alarm is
generated if the space temperature falls below the lower
limit or a High Space Temperature alarm is generated if
the space temperature rises above the upper limit.
When Unoccupied, an unoccupied low space temperature
alarm is generated when the space temperature falls below
the alarm configuration Unoccupied Low SPT Alarm
Limit or an unoccupied high space temperature alarm is
generated when the space temperature rises above the
alarm configuration Unoccupied High SPT Alarm Limit.