Lennox System Operation Monitor (Lsom) - Lennox Dave Signature Collection XC15 Installation Instructions Manual

Lennox System Operation Monitor
(LSOM) (100034−2)
The diagnostic indicator detects the most common fault
conditions in the air conditioning system. When an
abnormal condition is detected, the module communicates
the specific condition through its ALERT and TRIP lights.
The module is capable of detecting both mechanical and
electrical system problems.
IMPORTANT
This monitor does not provide safety protection.
The is a monitoring device only and cannot control
or shut down other devices.
LSOM LED FUNCTIONS
The LSOM LED functions are described in the following
table. Refer to table 8 for the complete explanation of
troubleshooting codes.
Table 6. LED Functions
LED
Label Function
Color
Indicates voltage within the range of
19−28VAC is present at the system monitor
Power Green
power connection.
Communicates an
condition through a unique flash code. The
alert LED flashes a number of times
consecutively; then pauses; then repeats
Alert Yellow
the process. This consecutive flashing
correlates
condition.
Indicates there is a demand signal from the
thermostat but no current to the compressor
Trip Red
is detected by the module.
RESETTING ALERT CODES
Alert codes can be reset manually or automatically:
Manual Reset
Cycle the 24VAC power to LSOM off and on. After power
up, existing code will display for 60 seconds and then clear.
Manual reset can be achieve by any of the following
methods:
S
Disconnecting R wire from the LSOM's R terminal.
S
Turning the indoor unit off an on again.
Automatic Reset
After an alert is detected, the LSOM continues to monitor
the compressor and system. When/if conditions return to
normal, the alert code is turned off automatically.
COMPRESSOR WIRE ROUTING
The scroll compressor's run R, common C, and start S
wires are factory routed through the holes in the LSOM
marked R, C, and S as illustrated in figure 37. The common
C wire need not be routed through the module for it to
operate properly.
506044−01 06/08
abnormal system
to a particular abnormal
Page 20
Figure 37. Compressor Wire Routing
(Factory Installed)
TERMINAL CONNECTIONS
This section address terminal connections and their
purpose.
Power (R and C Terminals)
LSOM requires a constant nominal 24VAC power supply.
The wiring to the module's R and C terminals must be
directly from the indoor unit or thermostat. The module can
not be powered by the C terminal, defrost board or other
control board without experiencing nuisance alerts.
When constant 24VAC (R wire) is not present in the
outdoor unit, use one of the spare wires in the thermostat
cable to bring power to the module. Connect the other end
of the spare wire to R at the indoor unit or thermostat.
Thermostat Demand Wiring (Y Terminal)
LSOM requires a thermostat demand signal to operate
properly. The thermostat demand signal input terminal,
labeled Y on the module, should always be connected to
the compressor contactor coil so that when the coil is
energized, the demand signal input is 24VAC. When
thermostat demand is not present, Y should be less than
0.5VAC.
Alert Communication (L Terminal) (Optional)
The L terminal is used to communicate alert codes to the
room thermostat. On selected Lennox Comfort Sense,
Elite and Merit thermostats there is an L terminal for direct
input from the LSOM. See specific thermostat user guide
on how alerts are displayed.
Data Port Terminal
The data port terminal is for future use and has not been
implemented at this time.
INSTALLATION VERIFICATION
To verify correct LSOM installation, perform the two
following functional tests:
Function Test 1
1. Disconnect power from the compressor.
2. Force a thermostat call for cooling.
3. The red 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 7 to verify the wiring.
Function Test 2
1. Disconnect power from the compressor and 24VAC
power from LSOM.
2. Remove the wire from the Y terminal of LSOM and
reapply power to the compressor, allowing the
RUN
COMMON
START