Carrier 50CR - Manual (Page 18)

18
10 seconds). Once communications with User Interface are
successful, COMM LED will be lit and held on. At the same time,
amber STATUS LED will be lit and held continuously on until a
request for operating mode is received. The STATUS LED will be
on any time unit is in idle mode.
If, at any time, communications are not successful for a period
exceeding 2 minutes, the Infinity control will only allow emergency
heating or cooling operation using a common thermostat and the R,
C, Y, O, W terminal strip connections and will display Status Code
16, System Communication Fault, on amber STATUS LED. No
further troubleshooting information will be available at User
Interface until communications are re--established.
If COMM LED does not light within proper time period and status
code is not displayed;
1. Check system transformer high-- and low--voltage to be sure
the system is powered.
2. Check fuse on control board to be sure it is not blown. If fuse
is open, check system wiring before replacing it to be sure a
short does not cause a failure of replacement fuse.
If COMM LED does not light within proper time period and status
code is displayed,
1. Check system wiring to be sure User Interface is powered
and connections are made A to A, B to B, etc. and wiring is
not shorted. Mis--wiring or shorting of the ABCD
communications wiring will not allow successful
communications.
NOTE: Shorting or mis--wiring low--voltage system wiring will not
cause damage to unit control or user interface but may cause low
voltage fuse to open.
C. ECM Motor Troubleshooting
The ECM motor used in this product consists of two parts: the
control module and the motor winding section. Do not assume
motor or module is defective if it will not start. Use the designed--in
LED information aids and follow troubleshooting steps described
below before replacing motor control module or entire motor.
Motor control module is available as a replacement part.
VERIFY MOTOR WINDING SECTION
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
After disconnecting power from the ECM motor, wait at least
5 minutes before removing the control section. Internal
capacitors require time to discharge.
! WARNING
Before proceeding to replace a motor control module:
1. Check motor winding section to be sure it is functional.
2. Remove motor control module section and unplug winding
plug. Motor shaft should turn freely, resistance between any
two motor leads should be similar and resistance between
any motor lead and unpainted motor end should exceed
100,000 ohms.
3. Failing any of these tests, entire ECM motor must be
replaced.
4. Passing all of the tests, motor control module alone can be
replaced.
MOTOR TURNS SLOWLY
1. Low static pressure loading of blower while access panel is
removed will cause blower to run slowly. Particularly at low
airflow requests. This is normal, do not assume a fault exists.
2. Recheck airflow and system static pressure using User
Interface service screens with access panel in place.
NOTE: Blower motor faults will not cause a lockout of blower
operation. The unit control will attempt to run the blower motor as
long as User Interface maintains a demand for airflow. The unit
control will not operate electric heaters while a fault condition
exists. The unit control communicates with the motor at least once
every five seconds, even when the motor is idle. If, during operation,
the unit control does not communicate with the motor for more than
25 seconds, the motor will shut itself down and wait for
communications to be reestablished.
D. Using Motor LED in Troubleshooting
The MOTOR LED is connected to the blower motor
communication line and works with the unit control microprocessor
and the STATUS LED to provide unit operation and
troubleshooting information. When the motor is commanded to
operate, the MOTOR LED will be turned on and will flash each time
instructions are sent to the motor. When the motor is commanded to
stop, the MOTOR LED will be turned off.
If the MOTOR LED is lit, flashing, and the motor is running, or if
the MOTOR LED is off and the motor is stopped, operation is
normal and no motor fault exists.
If the MOTOR LED is lit, flashing, and the motor does not run, or
if the MOTOR LED is off and the motor is running, check the
STATUS LED for the Status Code. Refer to the troubleshooting
instructions for the indicated Status Code in Section E, Unit
Troubleshooting.
E. Unit Troubleshooting
Unit faults indicated by flashing codes on the amber system
STATUS LED can be resolved using troubleshooting information
provided below. Codes are listed in order of their priority, highest
to lowest. Though multiple faults can exist at any time, only the
highest priority code will be displayed on STATUS LED. Clearing
the indicated fault when multiple faults exist will cause the next
highest priority Status Code to be flashed. All existing faults, as well
as a fault history, can be viewed at User Interface.
STATUS CODE 45, CONTROL BOARD TEST FAULT
Unit control has failed internal start--up tests and must be replaced.
No other service procedure will correct.
STATUS CODE 37, HEATER OUTPUT SENSED “ON” WHEN
NOT ENERGIZED:
Unit control is provided with circuitry to detect presence of a 24--vac
signal on electric heater stage 1 and stage 2 outputs.
If unit control detects a 24--vac signal on either heater stage output
and it is not supplying signal, Status Code 37 will be displayed on
STATUS LED. Unit control will turn off output and command
blower motor to supply an airflow determined to be safe for current
operation mode with electric heaters energized.
To find the fault:
1. Stop all system operations at User Interface and check heater
stage 24--vac outputs.
2. Disconnect electric heater at power and check heater wiring
for faults. See Status Code 36 for more information.
STATUS CODE 44, MOTOR COMMUNICATION FAULT
The MOTOR LED is connected to the blower motor
communication line and works with the unit control microprocessor
and STATUS LED to provide unit operation and troubleshooting
information.
When motor is commanded to operate, the MOTOR LED will be
turned on and will flash each time instructions are sent to the motor.
50C
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