Aerco KC Series Installation, Operation & Maintenance Instructions Manual page 54

7.7.3 AIR SUPPLY AND BLOWER PROOF
SWITCH
1. If the unit has sealed combustion, check the
ducting for any signs of blockage
2. If combustion air is brought in through an
opening in a wall, be sure that the size of the
opening is adequate and that louvers are
open while the unit is firing. (Refer to
AERCO GF-1050 for sizing.)
3. If the combustion air supply is okay, remove
wires #17 and #24 from the blower proof
switch.
4. Connect an ohmmeter across the blower
proof switch and restart 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 blockage is present,
clean the switch and retest.
7. If the blower proof switch shows continuity,
disconnect electrical power to the unit.
8. Disconnect the 15-pin connector from the
control panel.
9. Referring to system schematic 161412 in
Appendix F, 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 connectors, 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. Restore electrical power to the unit and start
the unit.
15. If the SYSTEM FAULT LOW AIR
PRESSURE fault persists, replace the
control panel.
7.7.4 PURGE INTERLOCKS
If SSOV proof of closure switch or the air\fuel
valve purge position switch fail to prove during
the start sequence, the unit will shut down and
TROUBLESHOOTING
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 restart the unit.
3. If the Annunciator displays the message
PURGE INTLK OPEN and the air\fuel valve
does not rotate, proceed to section 7.7.7.
4. If the air\ fuel valve rotates to its full open
position and engages the valve open proving
switch, and the Annunciator still displays
SYSTEM FAULT, PURGE INTERLOCKS,
proceed to section 7.7.6.
7.7.5 SSOV PROOF OF CLOSURE
SWITCH
1. Disconnect electrical power to the unit.
2. Loosen the two set screws holding the safety
shutoff valve actuator to the safety shutoff
valve body.
3. Rotate the actuator portion clockwise
exposing the cover plate and tighten the two
previously loosened set screws.
4. Remove the cover plate exposing the control
wiring
.
5. Referring to the system schematic 161412 in
Appendix F, 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
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.
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