AERCO KC1000 Boiler equipped with Mod-Box Controller - Manual (Page 55)

TROUBLESHOOTING
50
5. If the air/fuel valve does not rotate or is
extremely difficult to rotate, replace the
air/fuel valve.
6. Disconnect the 12 pin connector from the
control panel. Referring to schematic
161413 in Appendix H, check all wires for
continuity.
7. Check all the pins in the 12 pin connector for
proper insertion or signs of wear.
8. If all connections, continuity, and the rotation
of the air/fuel valve in Step 4 were okay,
open the control box to expose the wiring
and components.
9. Referring to Appendix I, Item #4, Locate the
air/fuel valve stepper motor driver board.
10. Ensure the connectors and wires are not
loose and are making good contact.
11. If the wiring to the driver board is okay, place
a voltmeter across terminals 7 and 8 on the
back of the temperature control.
12. Apply AC Power to the unit.
13. Place the ON/OFF switch in the OFF
position.
14. Measure the DC voltage across these two
terminals. It should be 15 volts ± 2 volts.
15. Place the ON/OFF switch in the ON position
16. Measure the DC voltage again. It should be
approximately 3 volts DC during PURGE
and 1 to 1.3 volts during ignition.
17. If the voltage is correct, replace the stepper
motor driver board.
18. If the voltage remains at 15 volts
± 2 volts
during PURGE or remains at 3 volts during
ignition replace the relay board.
19. If the DC voltage is at 0 volts, replace the
temperature controller.
8.8.8 AIR/FUEL VALVE IGNITION
POSITION SWITCH
1. Disconnect AC power to the unit.
2. Remove the air/fuel valve cover
3. Referring to system schematic 161413 in
Appendix H, locate wires #60 and #61.
Remove wires #60 and #61 from the air/fuel
valve ignition position switch, noting their
position. (The air/fuel valve ignition position
switch is the one closest to the shell of the
unit.)
4. Place an ohm meter across the terminals of
the switch, where wires #60 and #61 were
located.
5. Manually depress the switch and check the
ohm meter for continuity.
6. If the switch shows continuity, proceed to
Step 8.
7. If the switch does not show continuity,
replace the switch.
8. Disconnect the 12 pin connector from the
control panel.
9. Referring to system schematic 161413 in
Appendix H, locate wires #60 and #61.
Check wires #60 and #61 for continuity.
10. Check for loose connectors at the switch
end of wires #60 and #61.
11. Check the 12 pin connector end for worn
and/or properly inserted pins.
12. If continuity, pins and connections are okay,
reattach wire #60 and #61 to the air/fuel
valve ignition position. Reconnect the 12 pin
connector to the control panel and start the
unit.
13. If the system fault still persists , contact your
local AERCO representative.