Lennox Signature Collection XP15 Installation Instructions Manual page 20

Table 13. LSOM LED Troubleshooting Codes
Status LED Status LED
Status LED Troubleshooting Information
Condition Description
Green Power LED ON LSOM has power
Green Power LED OFF LSOM not powering up
System and compressor
check out OK
Thermostat demand signal
Y1 is present, but
compressor not running
NO TE - During 5-minute
delay in LSOM the red trip
LED will be on.
Red Trip LED ON
Red Trip and Yellow
Alert LEDs Flashing Simultaneous flashing,
Yellow Alert Flash
Code 1"
Yellow Alert Flash
Code 2*
Yellow Alert Flash
Code 3*
Yellow Alert Flash
Code 4*
Long Run Time - Compres-
sor is running extremely
long run cycles
System Pressure Trip -
Discharge or vapor pressure
out of limits or compressor
overloaded
Short Cycling - Compres-
sor is running only briefly
Locked Rotor
Open Circuit
Yellow Alert Flash
Code 5*
Yellow Alert Flash Open Start Circuit - Cur-
Code 6* rent only in run circuit
Yellow Alert Flash Open Run Circuit - Current
Code 7* only in start circuit
Yellow Alert Flash Welded Contactor -
Code 8* Compressor always runs
Yellow Alert Flash Low Voltage - Control cir-
Code 9* cuit <17VAC
24VAC control power is present at the LSOM terminal.
Determine/verify that both R and C LSOM terminals are connected and voltage is present
at both terminals.
1 Verify Y terminal is connected to 24VAC at contactor coil.
2 Verify voltage at contactor coil falls below 0.5VAC when off.
3 Verify 24VAC is present across Y and C when thermostat demand signal is present; if not
present, R and C wires are reversed.
1 Compressor protector is open.
2 Outdoor unit power disconnect is open.
3 Compressor circuit breaker or fuse(s) is open.
4 Broken wire or connector is not making contact.
5 Low pressure switch open if present in the system.
6 Compressor contactor has failed to close.
Indicates that the control circuit voltage is too low for operation.
1 LOW
refrigerant charge.
2 Evaporator blower is not running.
3 Evaporator coil is frozen.
4 Faulty metering device.
5 Condenser coil is dirty.
6 Liquid line restriction (filter drier blocked if present).
7 Thermostat is malfunctioning.
1 Check high head pressure or discharge line sensor.
2 Condenser coil poor air circulation (dirty, blocked, damaged).
3 Condenser fan is not running.
4 Return air duct has substantial leakage.
5 If low pressure switch is present, see Flash Code 1 information.
1 Thermostat demand signal is intermittent.
2 Time delay relay or DCB is defective.
3 If high pressure switch is present, see Flash Code 2 information.
4 If low pressure switch is present, see Flash Code 2 information.
1 Run capacitor has failed.
2 Low line voltage (contact utility if voltage at disconnect is low).
3 Excessive liquid refrigerant in the compressor.
4 Compressor bearings are seized.
1 Outdoor unit power disconnect is open.
2 Unit circuit breaker or fuse(s) is open.
3 Unit contactor has failed to close.
4 High pressure switch is open and requires manual reset.
5 Open circuit in compressor supply wiring or connections.
6 Unusually long compressor protector reset time due to extreme ambient temperature.
7 Compressor windings are damaged.
1 Run capacitor has failed.
2 Open circuit in compressor start wiring or connections.
3 Compressor start winding is damaged.
1 Open circuit in compressor start wiring or connec_ons.
2 Compressor start winding is damaged.
1 Compressor contactor failed to open.
2 Thermostat demand signal not connected to LSOM.
1 Control circuit transformer is overloaded.
2 Low line voltage (contact utility if voltage at disconnect is low).
*Flash code number corresponds to a number of LED flashes, followed by a pause, and then repeated. Reset ALER Tflash code by removing 24VAC power
from LSOM; last code will display for 1 minute after LSOM is powered on.
Note: If the unit is equipped with a two-stagged compressor, upon Y2 signal detection and after five seconds, the LSOM will send 24 VAC to the solenoid.
Once the solenoid is fully energized, the L SOM reduces voltage to between 4 to 18 VDC . Every 15 minutes the solenoid voltage will be increase to 24 volts
for a few seconds to ensure solenoid valve is engaged until Y2 signal is no longer present.
505328M 04_8
Page 20