Lennox Signature Collection XP15 Installation Instructions Manual page 21

LSOM--LED Functions
A IMPORTANT
See table 13 on page 20 for the complete explanation of
troubleshooting codes.
LED
Function Description
Color
Indicates voltage within the range of
Green Power 19-28VAC is present at LSOM con-
nection.
Yellow Alert
Communicates an abnormal system
condition through a unique flash code.
The alert LED flashes a number of
times consecutively; then pauses;
then repeats the process. This
consecutive flashing correlates to a
particular abnormal condition.
Indicates there is a demand signal
from the thermostat but no current to
Red Trip the compressor is detected by the
LSOM.
Resetting Alert Codes
Alert codes can be reset manually or automatically:
Cycle the 24VAC power to LSOM off and on. Af-
Manual ter power up, existing code will display for one
minute and then clear.
After an alert is detected, the LSOM continues
Automatic to monitor the compressor and system. Whentif
conditions return to normal, the alert code is
turned off automatically.
LSOM--L Terminal Connection
The L connection is used to communicate alert codes to
the room thermostat. On selected Lennox SignatureStat"
thermostats, a blinking check LED will display on the room
thermostat and on select White-Rodgers room
thermostats, an icon on the display will flash. Either will
flash at the same rate as the LSOM yellow alert LED,
NOTE - ROOM THERMOSTATS WITH SERVICE OR
CHECK LIGHT FEATURE--The room thermostat may
blink the Check or Service LED or it may come on sofid,
Confirm fault by observing and interpreting the code from
the LSOM yellow alert LED at the unit,
LSOM--Installation Verification
To verify correct LSOM installation, two functional tests
can be performed.
TEST 1 :
1. Disconnect power from the compressor and force a
thermostat call for cooling.
2. The red trip LED should turn on indicating a
compressor trip as long as 24VAC is measured at the
Y terminal, If the red LED does not function as
described, refer to table 13 on page 20 to verify the
wiring,
TEST 2:
1. Disconnect power from the compressor and 24VAC
power from the LSOM
2. Remove the wire from the Y terminal of LSOM and
reapply power to the compressor, allowing the
compressor to run. The yellow alert LED will begin
flashing a code 8 indicating a welded contactor,
3. While the LSOM is off, reattach the wire to the Y
terminal,
4. Reapply power to the compressor and 24VAC power
to the LSOM; the yellow alert LED will flash the
previous code 8 for one minute and then turn off. If the
yellow LED does not function as described, refer to
table 13 on page 20 to verify the wiring,
DEFROST CONTROL BOARD (DCB) FUNCTION
The DCB measures differential temperatures to detect
when the system is performing poorly because of ice
build-up on the outdoor coil. The DCB self-calibrates when
the defrost system starts and after each system defrost
cycle. The DCB components are illustrated in figure 31.
Note - Component Locations Vary by Board Manufacturer.
TEST PINS
DEFROST
TERMINATION
PIN SETTINGS
SENSOR
PLUG IN (COIL
AND AMBIENT
SENSORS)
DELAY
PINS
REVERSING
VALVE
PRESSURE
SWITCH
CIRCUIT
CONNECTIONS
rEs_ PI [_ O rAN
°
o_7 o
O wl
0-Ps
¢0_MON _2
TStPS O_ C _ 0 v_ _2
LOW
AMBIENT
THERMOSTAT
PINS
_DIAGNOSTIC
LEDS
24V TERMINAL
STRIP
CONNECTIONS
Figure 31. Defrost Control Board (DCB)
The DCB monitors ambient temperature, outdoor coil
temperature, and total run time to determine when a
defrost cycle is required. The coil temperature probe is
designed with a spring clip to allow mounting to the outside
coil tubing. The location of the coil sensor is important for
proper defrost operation.
NOTE - The DCB accurately measures the performance of
the system as frost accumulates on the outdoor coil. This
typically will translate into longer running time between
defrost cycles as more frost accumulates on the outdoor
coil before the DCB initiates defrost cycles.
Page 21
XP15 SERIES