Carrier Infinity 50XT-A Installation Instructions Manual page 14

UTILITY RELAY
UTILITY SIGNAL
OPEN RELAY
*
SUPPLIED BY UTILITY PROVIDER
B. Control Start- -Up and
Troubleshooting
On power up, green COMM LEDs will be turned off until
successful system communications are established (this should
happen within 10 seconds). Once communications with UI are
successful, both COMM LEDs will be lit and held on. At the same
time, amber STATUS LEDs 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 terminal strip connections on the two control
boards (see Non- -Communicating Emergency Cooling/Heating
Mode) and will display Status Code 16, System Communication
Fault, on amber STATUS LED. No further troubleshooting
information will be available at UI until communications are
re- -established.
If either COMM LED does not light within proper time period and
status codes are not displayed;
1. Check system transformer high- - and low- -voltage to be sure
the system is powered.
2. Check ABCD connection on both boards.
3. Check fuse on fan coil 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 UI is powered and
connections are made A to A, B to B, etc. and wiring is not
shorted. Mis- -wiring
communications wiring
communications.
*
Fig. 16 - - 2- -Stage HP/AC Control Board
System Communications
or shorting of the ABCD
will not allow successful
LLS
Liquid Line Solenoid
NOTE: Shorting or mis- -wiring low- -voltage system wiring will
not cause damage to unit control or UI but may cause low voltage
fuse to open.
C. Indoor Fan Motor (IFM) Troubleshooting
The indoor fan is driven by an Electronic Computated Motor
(ECM) which 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
WARNING
!
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.
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.
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A05247