
Page 27
HARMONY III
T
SERIES
Troubleshooting Diagrams
-
Are thermostats wired correctly?
-
Does zone control system respond appropriately to demand?
-
Heat/cool thermostat used? (Must not use heat pump thermostat.)
-
Does electronic thermostat have relay switching output? If not, isolation relays may
need to be used.
-
24VAC supplied to each thermostat terminal R from zone control system?
-
Check each thermostat for output signal when calling. Heating output? Cooling output?
System Troubleshooting − Harmony III
t
Zone Control System Option 1 −
Lennox Variable-Speed Gas Furnace and Lennox Condensing Unit
-
Fuses OK?
-
Error code present? If
so, see troubleshooting/
diagnostic section of this
manual (Page 25).
-
Are jumpers set cor-
rectly for furnace and
cooling? (Page 11)
-
Are PIAB jumpers
set correctly?
-
Only 1 jumper per
Zone? (Zone Con-
trol System Jump-
er Settings
(Page 8)
-
Is discharge
probe
installed?
-
Is probe lo-
cated in dis-
charge air ple-
num as de-
scribed on
Page 5?
-
Is it wired cor-
rectly?
-
Does outdoor unit respond to demand?
-
Is it operating properly?
-
Are appropriate outputs energized in response to demand?
-
Does zone control system energize appropriate outputs? During
Cooling? During Heating?
-
24VAC from furnace transformer to R?
-
Does furnace respond to outputs?
-
Does blower speed change as zone demand changes? If no,
does DS output vary from 0 to 25VDC?
-
Are Reduction jump-
ers set correctly?
-
Do jumpers provide
appropriate speed re-
duction? If no, check
indoor unit before re-
placing zone control
board.
-
Do dampers respond to demand? 0
volts AC = open. 24 volts AC =
closed. Dampers should drive closed
when 24 volts is jumpered to damper
motor.
-
Is wiring correct & in good condition?
Figure 23
-
Line Voltage to transformer?
-
24VAC from transformer to zone
control board?
-
Are all wire connections good?
Are all wire connections correct?
-
[No pressure Switch should be installed.]
BPS BPS
PS PS
DAMPERS
85
90
100
110
120
130
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
NotUsed
OFF
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Zone4
PIAB
Zone1
PIAB
Zone2
PIAB
Zone3
PIAB
SYSTEM
Configuration
E−HEAT
Stages
Heating
Staging Temp
50
55
60
Cooling
Staging Temp
0%
20%
40%
0%
25%
50%
75%
OFF
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
OFF
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Cont. Air
Reduction
Heating Air ‘
Reduction
DF
1
2
3
HP
2COOL
2HP
GAS
1COOL
1HP
TDO
Fault
Recall
Vacation
Mode
Selector
E−Heat
Selector
1/2 AMP
DS FUSE
S
P
ARE DS FUSE
3 AMP
P
ANEL FUSE
S
P
ARE P
ANEL FUSE
Thermostat 4
Thermostat 3
W C Y G R
W C Y G R
Balance
Point
Sensor
Pressure Switch
Diag4
Diag3
Diag2
Diag1
E−Heat
Vacation
damper 4
damper 3
Damper 2
Damper 1
Mode
Mode
Fan
Cooling
ElectHeating
Heating
Status
ESD CAUTION
TOUCH A GROUNDED METAL
OBJECT BEFORE TOUCHING
THE CIRCUIT BOARD
LENNOX
Harmony III
t
V3.0 2004
System Configuration & E−Heat jumper
piab jumper settings −
air reduction jumper
heat/cool staging
jumper settings − page
11.
120
VAC
24
VAC
C R
Damper1
NC
NO
C
das
Damper2
NC
NO
C
Damper3
NC
NO
C
Damper4
NC
NO
C
Thermostat 2
Thermostat 1
W C Y G R
W C Y G R
W C Y G R
W C Y G R
DISCHARGE AIR SENSOR
THERMOSTATS
Y1
Y2
C
R
R
G
W1
W2
C
DS
Y1
Y2
O
RC
W1−Def
RH
G
W1
W2
W3
DS
Equipment
Equipment
VARIABLE SPEED
FURNACE
2-STAGE CON-
DENSING UNIT