International comfort products F8MVL Installation Instructions Manual page 48

WARNING
!
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury, or death.
Blower access door switch opens 115−v power to
furnace control. No component operation can occur
unless switch is closed. Exercise caution to avoid
electrical shock from exposed electrical components
when manually closing this switch for service purposes.
b. Manually close blower access door switch.
NOTE: If R−W/W1 thermostat terminals are jumpered at the
time blower access door switch is closed, blower will run for 90
sec before beginning a heating cycle.
c. Perform component self−test as shown at the bottom
of the SERVICE label, located on the front of blower
access door.
d. Verify blower is rotating in the correct direction
17. If furnace is operating properly, RELEASE BLOWER AC-
CESS DOOR SWITCH. Remove any jumpers or reconnect
any disconnected thermostat leads. Replace blower ac-
cess door.
18. Downflow or horizontal furnaces with vent pipe through fur-
nace only:
a. Install and connect short piece of vent pipe inside
furnace to existing vent.
b. Connect vent connector to vent elbow.
19. Reinstall outer door.
20. Turn on gas supply and cycle furnace through one com-
plete heating and cooling cycle. Verify the furnace temper-
ature rise as shown in Adjustments Section. Adjust tem-
perature rise as shown in Adjustments Section. If outdoor
temperature is below 70_F, turn off circuit breaker to out-
door unit before running furnace in the cooling cycle. Turn
outdoor circuit breaker on after completing cooling cycle.
Cleaning Heat Exchanger
The following steps should be performed by a qualified
service agency:
NOTE: If the heat exchangers get a heavy accumulation of
soot and carbon, they should be replaced rather than trying to
clean them thoroughly. A build−up of soot and carbon
indicates that a problem exists which needs to be corrected,
such as improper adjustment of manifold pressure, insufficient
or poor quality combustion air, incorrect size or damaged
manifold orifice(s), improper gas, or a restricted heat
exchanger. Action must be taken to correct the problem.
If it becomes necessary to clean the heat exchangers
because of dust or corrosion, proceed as follows:
1. Turn OFF gas and electrical power to furnace.
2. Remove outer access door.
3. Disconnect vent connector from furnace vent elbow.
4. For downflow or horizontal furnace having an internal vent
pipe, remove internal vent pipe within the casing.
5. Disconnect wires to the following components. Mark wires
to aid in reconnection (be careful when disconnecting
wires from switches because damage may occur):
a. Draft safeguard switch.
b. Inducer motor.
c. Pressure switches.
d. Limit overtemperature switch.
e. Gas valve.
48
6. Remove screws that fasten the collector box assembly to
the cell panel. Be careful not to damage the collector box.
Inducer assembly and elbow need not be removed from
collector box.
7. Disconnect gas line from gas manifold.
8. Remove the four screws that attach the burner assembly
to the cell panel. The gas valve and individual burners
need not be removed from support assembly. Remove
NOx baffles, if installed.
NOTE: Be very careful when removing burner assembly to
avoid breaking igniter. See Figure 52−Figure 53 for correct
igniter location.
9. Using field−provided 25−caliber rifle cleaning brush, 36−in.
(914 mm) long, 1/4−in. (6 mm) diameter steel spring cable,
a variable speed reversible electric drill, and vacuum
cleaner, clean cells as follows:
NOTE:
purchased at local hardware stores.
Specifications are subject to change without notice.
f. Hot surface igniter.
g. Flame−sensing electrode.
h. Flame rollout switches.
Figure 52 − Igniter Position − Side View
Figure 53 − Igniter Position − Top View
a. Remove metal screw fitting from wire brush to allow
insertion into cable.
b. Insert the twisted wire end of brush into end of
spring cable, and crimp tight with crimping tool or
crimp by striking with ball−peen hammer. TIGHT-
NESS IS VERY IMPORTANT.
The materials needed in item 9 can usually be
(1.) Attach variable−speed, reversible drill to the end
of spring cable (end opposite brush).
(2.) Insert brush end of cable into the outlet opening
of cell and slowly rotate with drill. DO NOT force
cable. Gradually insert cable into upper pass of
cell. (See Figure 54)
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A05026
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