Benchmark 2.0 LN Installation, Operation & Maintenance Manual
CHAPTER 8 – TROUBLESHOOTING GUIDE
OMM-0046_0J
AERCO International, Inc.
•
100 Oritani Dr.
•
Blauvelt, NY 10913
Page
103
of
168
GF-123
Ph.: 800-526-0288
06/18/2015
TABLE 8-1. BOILER TROUBLESHOOTING
(Continued)
FAULT INDICATION
PROBABLE CAUSES
CORRECTIVE ACTION
STEPPER MOTOR
FAILURE
1.
Air/Fuel Valve out of calibration.
2.
Air/Fuel Valve unplugged.
3.
Loose wiring connection to the
stepper motor.
4.
Defective Air/Fuel Valve stepper
motor.
5.
Defective Power Supply Board or
fuse
6.
Defective IGST Board
1.
Refer to GF-112 and perform Stepper Test (para. 6.3.5) to
ensure stepper motor rotates properly between the 0%
(fully closed) and 100% (fully open) positions. Verify that
the VALVE POSITION bargraph and the dial on the
Air/Fuel Valve track each other to indicate proper
operation. If operation is not correct, perform the Stepper
Feedback Calibration (GF-112, paragraph 6.2.1).
2.
Check that the Air/Fuel Valve is connected to the Control
Box.
3.
Inspect for loose connections between the Air/Fuel motor
and the wiring harness.
4.
Replace stepper motor.
5.
Check DS1 & DS2 LEDs on Power Supply Board. If they
are not steady ON, replace Power Supply Board
6.
Check “Heartbeat” LED DS1 and verify it is blinking ON &
OFF every second. If not, replace IGST Board
