Flame Rod Does Not Detect Flame; Overheat Prevention Device (Thermal Fuse) Triggered - Noritz NR501-OD Service Manual

Error Codes
Display Remote
Window Controller
121, 122 12
The trouble diagnosis for "Error Code 12" is same as "Error Code 11".
<The occurrence condition for Error Code 121 and 122>
Error Codes
121 When the Unit fails the re-iginition after the Unit detected extinction.
122 When the Unit detects extinction 6 times in 5 minutes.
Error Codes
Display Remote
Window Controller

Overheat Prevention Device (Thermal Fuse) triggered

14 14
Check the overheat prevention device (Thermal Fuse) resistance.
Normal
CN10
Between Blue 15 - White 13
2 or less
When measuring the
resistance, disconnect the
connector and check the
male side.
Description
Description
Description
Abnormal
Circuit Board
14
13
1
12 BL
11 W
2
10 R
9 Y
3 BL
8
Main
7
4 R
6 BK Circuit
5 BK
5 W Board
4 W
3
W
6 O
2 BK
1 W
7 GY
<CN63>
1 2 3
8 BK
<CN135>
9
10 W <CN142>
<CN78>
11 BL
2
1
12 1 BL 2
3
BL
13 W 4 R
5 W
<CN101>
14
6 O
7 GY
15 8
BL BK <CN10>
9
10 W
<CN89B>
11 BL
<CN10>
12
6 BK 13 W
5 R 14
15 BL
4
3
2 W
1 W
<CN42> <CN89A>
40
12 W
11 Y
10 O
9 R
8
7
6 BK
5 V
4 G
3 O
2 Y
1 W
<CN59>
1
2
3 4 3 2 1
4 BL
4 R
3 BL BR Y BL R
5 O
2 BL
6 Y <CN27>
1 R
7
W
Po wer
<CN104>
Circuit
3 R
Board
2 BL
1 G
3
2
1
<CN75>
3 2 1
BL/W R/R G
<CN102>
Check for improper connection of wiring.
Check for the Heat Exchanger-Pr imar y is no rm al
(ex. The surface discolors blac k, clogging, etc.)
Replace the overheat pr evention device (Thermal Fuse).
*If the Thermal Fuse is blown again, correct the
Replace the Circuit Board set.
* It is not necessary to replace the
Displ ay Window Circuit Board.
Display Window
Fuse
Circuit Board
Data
Displ ay
W 3 1 W
BK 4 2 BK
<CN92>
Dip Switch
1 2 3 4
R BL BL BL
<CN142>
a c s u . e