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Benchmark 2500DF-3000DF Installation, Operation & Maintenance Manual
FAULT INDICATION
STEPPER MOTOR
FAILURE
OMM-0099_0A
GF-145
CHAPTER 8 – TROUBLESHOOTING GUIDE
TABLE 8-1: BOILER TROUBLESHOOTING – Continued
PROBABLE CAUSES
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
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913
Ph.: 800-526-0288
CORRECTIVE ACTION
1. Refer to GF-112 (C-More O & M) and perform the Stepper
Feedback Calibration procedure in Section 6, section 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 Valve 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.
Page 115 of 234
PR1: 05/21/2014
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