Lennox XC21 Installation Instructions Manual page 37

Table 10. Compressor Alert Codes (A175 Main Control LEDs and Communicating Thermostat User Interface)
Outdoor A175 Main
icomfort
Control LEDs
Toucht
Thermostat
DS15 DS13
Display
Yellow Red
Moderate/
OFF ON Critical Alert
Code 400
1 Flashes
Critical Alert
then
OFF
Code 401
Pause
2 Flashes
Critical Alert
then OFF
Code 402
Pause
Possible
Condition
Cause(s)
Thermostat
Compressor demand signal Y1
Internal is present, but
Overload Trip compressor not
running
Compressor is
running extremely
Long run time.
long run cycles.
Indicates the
compressor
System
protector is open
Pressure Trip
or missing supply
power to the
compressor.
Page 37
Solution
1
Compressor protector is open.
S
Check for high head pressure
S
Check compressor supply voltage
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 or high pressure switch open if pres-
ent in the system.
6
Compressor contactor has failed to close.
1
Low refrigerant charge.
2
Evaporator blower is not running.
S
Check blower relay coil and contacts
S
Check blower motor capacitor
S
Check blower motor for failure or
blockage
S
Check evaporator blower wiring and
connectors
S
Check indoor blower control
S
Check thermostat wiring for open cir-
cuit
3
Evaporator coil is frozen.
S
Check for low suction pressure
S
Check for excessively low thermostat
setting
S
Check evaporator airflow (coil block-
ages or return air filter)
S
Check ductwork or registers for block-
age.
4
Faulty metering device.
S
Check TXV bulb installation (size,
location and contact)
S
Check if TXV/fixed orifice is stuck
closed or defective
5 .
Condenser coil is dirty
6
Liquid line restriction (filter drier blocked if
.
present)
7 .
Thermostat is malfunctioning
S
Check thermostat sub−base or wiring
for short circuit
S
Check thermostat installation (loca-
tion and level)
1
High head pressure.
S
Check high pressure switch if present
in system
S
Check if system is overcharged with
refrigerant
S
Check for non−condensable in system
2
Condenser coil poor air circulation (dirty,
blocked, damaged).
3
Condenser fan is not running.
S
Check fan capacitor
S
Check fan wiring and connectors
S
Check fan motor for failure or block-
age
4
Return air duct has substantial leakage.
Clearing Status
Clears the error after
current is sensed in the
run and start winding for
two seconds, service
removed or power reset.
Clears the error after 30
consecutive normal run
cycles, or after power
reset.
Clears after four
consecutive normal
compressor run cycles,
or after power reset.
XC21 SERIES