Air Flow Abnormality; Combustion Abnormality - Noritz NR501-OD Service Manual

Error Codes
Display Remote
Window Controller
90
901, 902, 903 90
908
Combustion abnormality (Unit is locked)
ow abnormality
1 Check air inlet for blockage or obstruction.
2 Check exhaust for blockage or obstruction.
3 Check whether the fan motor is normal.
(ex. Clogging of fan blades, etc.)
4 Check the high elevation adjustment (Dip Switch Setting)
5 Check the vent length adjustment (Dip Switch Setting)
Setting list for Dip Switches

901 Combustion abnormality

(War
1 Check air inlet for blockage or obstruction.
2 Check exhaust for blockage or obstruction.
3 Check the Fan Motor is normal.
(ex. Clogging of fan blades, etc.)
4 Check the Burner is normal (clogged*).
The detail conditions for this error code are shown on page 24.
* How to check for clogged burner
* Check for clogged burner
Note) Remove the Manifold Plate.
Description
<Condition of occurrence for error code 90>
Detected abnor
If 1 to 5 check out okay, replace the Fan Motor.
Replace the Circuit Board set if the error code is
displayed again.
* It is not necessary to replace the Display Window Circuit
Board.
If 1 to 4 check out okay, replace the Circuit Board set
if the error code is displayed again.
Burner
49
ow when the unit will start.
<Condition of occurrence for error code 901>
When the unit has begun to operate,
- Air inlet for blockage or obstruction
- Exhaust for blockage or obstruction.