Lennox Signature XP21 Series Installation And Service Procedure page 37

Heat Pump Control
icomfortt icomfortt
LEDs
Thermostat Thermostat
DS15 DS13
Display Display
Yellow Red
4 flashes
Critical Alert
then
Off
Code 404
pause
5 flashes
Critical Alert
then
Off
Code 405
pause
6 flashes
Critical Alert
then Off
Code 406
pause
7 flashes
Critical Alert
then Off
Code 407
pause
8 flashes
Critical Alert
then
Off
Code 408
pause
9 flashes Moderate/
then Critical Alert
Off
pause Code 409
Fast simultaneous flashing of DS11,
DS13, DS14 and DS15
1. Pause duration is two (2) seconds.
2. Fast flash duration is 1/2 second. Slow flash duration is one (1) second.
3. Initially a moderate status is displayed and is escalated to critical if alarm exists for more than 10 minutes.
Possible Possible
Condition Condition
Cause(s) Cause(s)
Compressor has
a locked out due
to run capacitor
short, bearings
Locked rotor
are seized,
excessive liquid
refrigerant.
Compressor has
an open circuit
due to power dis-
connection, fuse
Open circuit
is open or other
similar condi-
tions.
Current not
Open start
sensed by Start
circuit
transformer.
Current not
Open run
sensed by run
circuit
transformer.
Welded Compressor
contactor always runs
Secondary 24VAC is below
3
low voltage 18VAC.
OEM Mode Factory test mode.
Solution Solution
1
Run capacitor has failed.
2
Low line voltage (contact utility if voltage at
disconnect is low).
S
Check wiring connections
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.
S
Check compressor contactor wiring and
connectors
S
Check for compressor contactor failure
(burned, pitted or open)
S
Check wiring and connectors between supply
and compressor
S
Check for low pilot voltage at compressor
contactor coil
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.
S
Check compressor motor winding resistance
1
Run capacitor has failed.
2
Open circuit in compressor start wiring or
connections.
S
Check wiring and connectors between supply
and the compressor S terminal
3
Compressor start winding is damaged.
S
Check compressor motor winding resistance
1
Open circuit in compressor start wiring or
connections.
S
Check wiring and connectors between supply
and the compressor R terminal
2
Compressor start winding is damaged.
S
Check compressor motor winding resistance
1
Compressor contactor failed to open.
2
Thermostat demand signal not connected to
module.
1
Control circuit transformer is overloaded.
2
Low line voltage (contact utility if voltage at
disconnect is low).
S
Check wiring connections
Page 37
Clearing Sta- Clearing Sta-
tus tus
Clears after
power reset or
four normal
compressor
cycles.
Clears after one
normal com-
pressor run
cycle or power
reset.
Clears when
amperage is de-
tected in RUN
and START
sensors, or after
power reset.
Clears when
amperage is de-
tected in RUN
and START
sensors, or after
power reset.
Clears after one
normal com-
pressor run
cycle or after
power reset.
Clears after
voltage is high-
er than 20VAC
for two sec-
onds, or after
power reset.
XP21