JANDY LITE (LD - LoNOx) TROUBLESHOOTING
Thermostat Control
White
6
5
High Limit
135 F
White
Black
White/Red
Red
4
3
Transformer
Red
2
Fusible
Link
1
Fuse
Hot Surface
Igniter
White/Black Black
Red
Yellow
Fireman’s
Switch
Connection
White
Purple
Air Pressure
Switch
240 VAC
Black/Yellow
White
High Limit
150 F
(red dot)
Thermistor
Laars
Pressure Switch
Gas
Valve
9a
MV
MV
IGN 240
L1
L2
IGN
FS
TH
VAL
Yellow
Burners
8
11
Gray
F1
F2
IGN 120
Brown
Red
24V
IND
7
Ignition
Control
GND
Whites
Flame Sensor
Black
Black/Yellow
Blower
Red Brown Blue
Black
Gray
Black
Black
White
Red
9b
STEP 1
24 Vac
at
Transformer?
STEP 2
NO
Fuse is blown. Look for short or overload of
controls. Do not jumper or bypass. Fuse
protects Transformer.
24 Volts
at TH of
Ignition Control?
Yes
NO
1. Do Thermistor test.
2. Is there voltage at
Black/Yellow wire?
YES
Replace Thermistor.
Replace Temp. Board.
NO
Fusible Link is blown. Look for roll out,
downdraft, soot and/or low gas pressure.
Replace Fusible Link.
Yes
NO
Is Blower On?
NO
Check Fireman’s Switch, remote(s)
and wire connections.
Is Igniter glowing
very brightly?
NO
Yes
1. Check each limit individually.
NO
5a & 5b
Yes
Check Blower Wiring.
Replace Blower. 9b
.
1. Is Ignition Control wired for proper voltage?
2. Is Igniter set to proper terminals for supply
voltage?
Perform Igniter Resistance test..
10
Replace Ignition
Control
STEP 11
Is Pump on? Perform Back Pressure Test.
If 2 PSI or more, replace switch. If less, check
pump, filter, heat exchanger for water flow
restrictions.
9a
Igniter OK
2. Check if damage to disc, heads, exchanger.
3. Perform Temperature Rise Test.
NO
Is there 120 Volts at
F2 of Ignition Control?
Check Supply Wiring.
Replace Ign. Control.
.
STEP 10
Yes
24 Vac at
VAL terminal of
Ignition Control?
NO
Igniter Failed
Replace Igniter
Replace Ignition Control
11
Yes
Yes
Go to Step 7
1. Check for vent blockage or dirty filter.
2. Perform air flow tests.
3. Replace Air Pressure Switch
NO
Yes
Yes
24 Vac at
Black Wire of
Pressure Switch?
NO
Yes
STEP 9
24 Vac at
White Wire of
Pressure Switch?
STEP 6
Is Temp Board calling for heat?
Yes
Yes
24 Vac at
White Wire of
Terminal Block?
STEP 5
NO
STEP 8
24 Vac at
White Wire of
Fusible Link?
STEP 4
1. Check Incoming Power Supply.
2. Check Transformer Wiring.
3. Replace Transformer.
Yes
24 Vac at
Red Wire of
Fusible Link?
STEP 3
NO
STEP 7
24 Vac at
Black/Yellow Wire of
Ign. Controller?
(terminal IND)
NO
Does Heater Fire?
Is Gas On?
Replace Gas Valve.
Mat #0755, Rev A 09/05
JANDY LITE (LD - LoNOx) TROUBLESHOOTING
Laars Lite 2 - Low NOx
White/Red
Red
Factory wired for 240 VAC
Transformer
This diagram shows the three field
changes to convert to 120 VAC.
Three changes are needed to convert
from 240 VAC to 120 VAC
1. Transformer
2. Hot Surface Ignitor
3. Blower
1
120 VAC
Red
Black White/Black
120 VAC
2
Hot Surface Ignitor
Black
F1
F2
IGN 120
IGN 240
L1
L2
IGN
FS
TH
24V
IND
Ignition
Control
VAL
GND
Blue
Red
Blower
Brown
Gray
Black
Black
3 120 VAC
Black
White
Red
Thermistor Test
(see chart to right)
Temp
Resistance
Temp
Resistance
50° F
19.898 K Ohms
78° F
9.735 K Ohms
51° F
OFF
ON
1000
Ω at 20 K
or above
V ∼
750 200
2M
200
V ---
200K
20
2
20K
2K
PNP
200
NPN
A ---
10A
2m
mA
Ω
200m
COM
v
Ω
Waterpik Technologies
Laars & Jandy Products
52° F
53° F
54° F
55° F
56° F
57° F
58° F
59° F
Remove thermistor from temperature board and measure the resistance
between the leads. Compare the temperature at that resistance (see chart to right)
with the actual temperature of the water.
60° F
61° F
62° F
63° F
64° F
Hot Surface Ignitor Test
1000
750
V ∼
200
2M
200
V --20
200K
2
20K
2K
PNP
200
NPN
A ---
10A
Ω at 2 K
or above
2m
mA
200m
COM
Ω
v Ω
Waterpik Technologies
Laars & Jandy Products
Make sure the Hot Surface Ignitor has cooled to ambient temperature.
Remove the H.I.S.. Measure the resistance across the two leads.
At ambient temperature the resistance should be 40 to 75 Ohms.
65° F
66° F
67° F
19.435 K Ohms
18.871 K Ohms
18.382 K Ohms
17.902 K Ohms
17.473 K Ohms
16.988 K Ohms
16.549 K Ohms
16.150 K Ohms
15.710 K Ohms
15.314 K Ohms
14.923 K Ohms
14.547 K Ohms
14.193 K Ohms
13.823 K Ohms
13.477 K Ohms
13.138 K Ohms
12.813 K Ohms
68° F
12.492 K Ohms
70° F
11.893 K Ohms
69° F
71° F
72° F
73° F
74° F
75° F
76° F
77° F
12.186 K Ohms
11.593 K Ohms
11.309 K Ohms
11.032 K Ohms
10.765 K Ohms
10.502 K Ohms
10.250 K Ohms
79° F
9.483 K Ohms
80° F
9.284 K Ohms
81° F
9.079 K Ohms
82° F
8.864 K Ohms
83° F
8.655 K Ohms
84° F
8.450 K Ohms
85° F
8.253 K Ohms
86° F
8.057 K Ohms
87° F
7.871 K Ohms
88° F
7.687 K Ohms
89° F
7.509 K Ohms
90° F
7.335 K Ohms
91° F
7.166 K Ohms
92° F
7.001 K Ohms
93° F
6.840 K Ohms
94° F
6.685 K Ohms
95° F
6.531 K Ohms
96° F
6.384 K Ohms
97° F
6.238 K Ohms
98° F
6.099 K Ohms
99° F
5.963 K Ohms
100° F
101° F
102° F
103° F
104° F
5.829 K Ohms
5.700 K Ohms
5.572 K Ohms
5.449 K Ohms
5.327 K Ohms
10.000 K Ohms
Mat #0755, Rev A 09/05