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CBX40UHV
Table 13. AHC Single Character Display — Error Codes (Communicating and Non-Communicating)
Alert
Code
Priority
Alert How to Clear
Critical
The air-handler has lost communica
tion with the rest of the system.
Equipment is unable to communicate. This may indicate the existence of other alarms
/ codes. In most cases errors are related to electrical noise. Make sure high voltage
power is separated from RSBus. Check for mis-wired and/or loose connections be
tween the thermostat, indoor unit and outdoor unit. Check for a high voltage source
of noise close to the system. Generally, this is a self-recoverable error.
Critical
There is a frequency/distortion problem
with the power to the air-handler.
This alarm/code may indicate transformer overloading. Check the voltage and line
power frequency. Check the generator operating frequency, if the system is running
on back-up power. Correct voltage and frequency problems. System resumes normal
operation 5 seconds after fault recovered.
Critical
The 24VAC to the air-handler control is
lower than the required range of 18 to
30VAC.
24-volt power low (range is 18 to 30 volts). Check and correct voltage. Check for addi
tional power-robbing equipment connected to system. This alarm / code may require
the installation of an additional or larger VA transformer.
Moder
ate
There is a delay in the air-handler re
sponding to the system.
Typically, this alarm/code does not cause any issues and will clear on its own. The
alarm/code is usually caused by a delay in the outdoor unit responding to the thermo
stat. Check all wiring connections. Cleared after unresponsive device responds to
any inquiry.
Critical
The iComfort™ thermostat has lost
communication with the air-handler for
more than 3 minutes.
Equipment lost communication with the iComfort
™
thermostat. Check the wiring con
nections, ohm wires and cycle power. The alarm stops all associated HVAC opera
tions and waits for a heartbeat message from the unit that's not communicating. The
alarm/fault clears after communication is re-established.
Critical
There is a hardware problem with the
air-handler control.
There is a control hardware problem. Replace the control if the problem prevents op
eration and is persistent. The alarm/fault is cleared 300 seconds after the fault recov
ers.
Moder
ate
An air-handler configuration jumper is
missing.
Configuration jumper(s) missing on control (applicable in non-communicating ap
plications only). Replace the jumper or put wire between terminals on control. Cleared
after jumper is connected.
Critical
The air-handler control parameters are
corrupted.
Reconfigure the system. Replace the control if heating or cooling is not available.
Critical
The air-handler control software is cor
rupted.
Recycle power. If failure re-occurs, replace the control. System reset is required to
recover.
Critical
The iComfort™ thermostat has found a
problem with the air-handler outdoor
sensor.
In normal operation after control recognizes sensors, the alarm will be sent if valid
temperature reading is lost. Compare outdoor sensor resistance to temperature/re
sistance charts in unit installation instructions. Replace sensor pack if necessary. At
the beginning of (any) configuration, the air-handler control will detect the presence
of the sensor(s). If detected (reading in range), appropriate feature will be set as
installed and shown in the ’About’ screen. The alarm / fault will clear upon configura
tion, or sensing normal values.
Critical
The system has lost communication
with the or air-handler indoor blower
motor.
Lost communication with indoor blower motor. Possible causes include power out
age, brown-out, motor not powered, loose wiring, condensation on air handler control
without cover on breaker. Problem may be on control or motor side. Cleared after
communication is restored.
Critical
The unit size code for the air-handler
and the size of blower motor do not
match.
Incorrect appliance unit size code selected. Check for proper configuring under unit
size codes for air handler on configuration guide or in installation instructions. The
alarm / fault clears after the correct match is detected following a reset. Remove the
thermostat from the system while applying power and reprogramming.
Critical
The unit size code for the air-handler
has not been selected.
No appliance unit size code selected. Check for proper configuring under: Unit size
codes for air handler on configuration guide or in installation instructions. Critical
Alert. The alarm/fault clears after the correct match is detected following a reset. Re
move the thermostat from the system while applying power and reprogramming.
Critical
The air-handler's blower motor will not
start.
The system will go into watchguard mode. Indoor blower motor unable to start. This
could be due to seized bearing, stuck wheel, obstruction etc. Replace motor or wheel
if assembly does not operate or meet performance standards. The alarm/fault clears
after the indoor blower motor starts successfully.
Minor
The indoor blower motor is over heat
ing.
Indoor blower motor over temperature (motor tripped on internal protector). Check
motor bearings and amps. Replace if necessary. The alarm / fault clears after blower
demand is satisfied.
Critical
There is a problem with air-handle) dis
charge air sensor.
Compare outdoor sensor resistance to temperature/resistance charts in installation
instructions. Replace sensor if necessary. The alarm/fault is cleared 30 seconds after
fault is detected as recovered.
Minor
The blower cannot provide the re
quested CFM due to high static.
Warning Only. Restricted airflow - Indoor blower is running at a reduced CFM (cut
back mode). The variable-speed motor has pre-set speed and torque limiters to pro
tect the motor from damage caused by operating outside of design parameters (0 to
0.8” e.g.. total external static pressure). Check filter and duct system. To clear, replace
filter if needed or repair/add duct. The alarm/fault is cleared after the current service
demand is satisfied.
Minor
The indoor and outdoor unit capacities
do not match.
Check for proper configuring in installation instructions. Alarm is just a warning. The
system will operate, but might not meet efficiency and capacity parameters. The
alarm will clear after commissioning is complete.
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