Troubleshooting Chart - No Display - Lochinvar Shield SWR125 Installation & Service Manual

12
Troubleshooting
Table 12A Troubleshooting Chart - No Display
FAULT
- No 120 VAC supplied to unit.
No Display
- Bad display board.
- Bad main control board.
- Blown fuse.
- Tank temperature set point satisfied.
No Burner
Operation
- Unit locked out on fault.
- Flue sensor open.
Unit Does
Not Modulate
Above 50%
(continued)
CAUSE
Installation & Service Manual
CORRECTIVE ACTION
• Check external line switch, fuse, or breaker.
• Check wiring harness connection between display
board and main control board. Connect harness at both
points.
• Replace board.
• Replace the main control board.
• Replace fuse F3 on the main control board, see
page 68 of this manual.
• Review temperature setting.
• Consult display for specific fault. Refer to fault
descriptions on page 72 of this manual for corrective
actions.
• Verify that the flue sensor is located in the flue outlet.
• Check wiring connections at the flue sensor.
• Check the resistance of the flue sensor and compare
to Table 12D on page 70 of this manual.
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