AERCO KC1000 Boiler equipped with Mod-Box Controller - Manual (Page 53)

TROUBLESHOOTING
48
4. Connect an ohmmeter across the blower
proof switch and start the unit.
5. The blower proof switch should show
continuity while the blower is running.
6. If the blower proof switch does not show
continuity, remove the switch and check for
signs of blockage. If there is blockage, clean
the switch and retest.
7. If the blower proof switch shows continuity,
disconnect AC power to the unit.
8. Disconnect the 15 pin connector from the
control panel.
9. Referring to system schematic 161413 in
Appendix H, locate wires #17 and #24 and
check both for continuity.
10. Check the switch end of wires #17 and #24
for loose connections.
11. Check the connector end for worn pins
and/or proper pin insertion.
12. If continuity, the connector and pins are
okay, reconnect wires #17 and #24 to the
blower proof switch.
13. Reconnect the 15 pin connector to the
control panel.
14. Reconnect AC power to the unit and start
the unit.
15. If the SYSTEM FAULT LOW AIR
PRESSURE fault still persists, replace the
control panel.
8.7.4 PURGE INTERLOCKS
If the SSOV proof of closure switch or the air/fuel
valve open position switches fail to prove closed
during the start up sequence, the unit will shut
down and the Annunciator will display the
message SYSTEM FAULT, PURGE
INTERLOCKS. To determine the cause of the
fault perform the following:
1. Remove the air/fuel valve cover.
2. Clear the Annunciator and start the unit.
3. If the Annunciator displays the message
PURGE INTLK OPEN and the air/fuel valve
does not rotate, proceed to section 8.7.7.
4. If the air/fuel valve rotates to its full open
position and engages the air/fuel valve open
proving switch, and the Annunciator still
displays SYSTEM FAULT, PURGE
INTERLOCKS, proceed to section 8.7.6.
8.7.5 SSOV PROOF OF CLOSURE
SWITCH
1. Disconnect AC power to the unit.
2. Loosen the two set screws securing the
safety shut-off valve actuator to the safety
shut-off valve body.
3. Rotate the actuator portion clockwise
exposing the electrical cover plate and
tighten the two previously loosened set
screws.
4. Remove the electrical cover plate exposing
the control wiring
5. Referring to the system schematic 161413 in
Appendix H, remove wires #21 and #22 from
the proof of closure switch.
6. Connect an ohm meter across the NC,
normally closed, and the C, common,
terminals.
7. The switch should show continuity. If it does
show continuity proceed to step 16.
8. If the switch does not show continuity,
remove the actuator from the valve body.
9. Looking at the actuator from the bottom,
push on the lever closest to the bottom of
the actuator.
10. Observe the ohm meter while pushing on
the lever. Pushing downward on the lever
should make continuity. Releasing the lever
should break continuity.
.
11. If continuity makes and breaks, slightly bend
the arm toward the bottom of the actuator.
12. Reset the actuator onto the valve body while
observing the ohm meter.
13. If continuity is now okay, reconnect wires
#21 and #22, replace the electrical cover
plate and reassemble the actuator to the
valve body.