Table 3A - Troubleshooting Chart - No Display - Lochinvar 402 Service Manual

3
Troubleshooting
Table 3A Troubleshooting Chart - No Display
FAULT
- No 120 VAC supplied to unit.
No Display
- Bad wiring connection.
- Blown fuse.
- Bad display board.
- Bad main control board.
- Main control board temperature setpoint
satisfied.
- Remote thermostat satisfied.
No Burner
Operation
- Outside air temperature above Warm
Weather Shutdown (WWSD) setpoint for
main control board.
- Unit locked out on fault.
- Boiler controlled by BMS.
Unit Does
Not Stage to
- Outlet temperature too high.
100%
- Delta T too high.
34
Copper-fin II/IIE Boiler and Water Heater
CAUSE CORRECTIVE ACTION
• Check external line switch, fuse, or breaker.
• Check position of ON/OFF switch. Turn switch to the
ON position.
• Check 120 VAC through the ON/OFF switch.
voltage through switch, replace switch.
• Check wiring harness connection between the display
board and the main control board. Connect the harness
at both points.
• Replace fuse F6 on the main control board, see
FIG. 3-1 on page 33 of this manual.
• Replace board.
• Replace main control board.
• Review temperature setting.
• Review remote thermostat setting.
• Check location of outside air sensor.
resistance of outdoor air sensor and compare to Table
3C on page 35 of this manual.
• Consult display for specific fault.
descriptions on pages 37 - 43 of this manual for
corrective actions.
• Check BMS parameter settings.
software required.
Service Manual
No
Check
Refer to fault
Optional PC