44
441 01 2101 05
Specifications are subject to change without notice.
15. Refer to furnace wiring diagram, and connect
thermostat leads if previously disconnected.
16. To check blower for proper rotation:
a. Turn on electrical supply.
b. Manually close blower access door switch.
NOTE
: If thermostat terminals are jumpered at the time
blower access door switch is closed, blower will run for 90
sec before beginning a heating or cooling 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
ACCESS DOOR SWITCH. Remove any jumpers or
reconnect any disconnected thermostat leads. Replace
blower access door.
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.
!
WARNING
18. Downflow or horizontal furnaces with vent pipe through
furnace 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
complete heating and cooling cycle. Verify the furnace
temperature rise as shown in Adjustments Section.
Adjust temperature rise as shown in Adjustments
Section. If outdoor temperature is below 70
F (21
C)
turn off circuit breaker to outdoor 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 of (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.
f. Hot surface igniter.
g. Flame
−
sensing electrode
h. Flame rollout switches.
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 5 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 and 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:
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. TIGHTNESS IS
VERY IMPORTANT.
Figure 52
−
Igniter Position
−
Side View
A05025
NOTE
: The materials needed in item 9 can usually be
purchased at local hardware stores.
(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)
(3.) Work cable in and out of cell 3 or 4 times to obtain
sufficient cleaning. DO NOT pull cable with great
force. Reverse drill and gradually work cable out.