10. Remove screws attaching burner box to cell panel. (See Fig.
5.)
NOTE: Burner box cover, manifold, gas valve, and burner
assembly should be removed as 1 assembly.
11. Clean heat exchanger openings with a vacuum and a soft
brush. (See Fig. 6.)
NOTE: After cleaning, inspect the heat exchangers to ensure they
are free of all foreign objects that may restrict flow of combustion
products.
12. Reverse items 4 through 10 for reassembly.
CAUTION: UNIT MAY NOT OPERATE
Failure to attach ground wire to an adequate casing
ground may cause the furnace control to lock out.
The ground wire from the gas valve MUST be attached to
the burner box attachment screw.
NOTE: Be sure burner box gasket is installed between burner box
and cell panel. See Fig. 5. If gasket is damaged, replace it.
NOTE: Inspect combustion-air intake housing. If foamed gasket
was removed, check for any damage. If gasket is damaged in any
way, it must be repaired. To repair, remove damaged gasket
section, apply sealant releasing agent such as PAM cooking spray
or equivalent (must not contain corn or canola oil, aromatic or
halogenated hydrocarbons, which could cause an inadequate seal
to occur) to burner box and apply a small bead of G.E. RTV 162,
G.E. RTV 6702, or Dow-Corning RTV 738 sealant to edge of
combustion-air intake housing. (See Fig. 7.)
13. Refer to furnace wiring diagram and reconnect wires to
flame rollout switch, gas valve, igniter, and flame sensor.
14. Reconnect pressure switch tubes to gas valve and intake
housing. Refer to tube routing label on main furnace door
for proper tube location. Be sure tubes are not kinked. (See
Fig. 8.)
15. Turn on gas and electrical supplies to furnace.
16. Check furnace operation through 2 complete heat operating
cycles. Look through sight glass in burner enclosure to
check burners. Burner flames should be clear blue, almost
transparent. (See Fig. 9.)
WARNING: FIRE OR EXPLOSION HAZARD
Failure to follow the safety warnings exactly could result
in serious injury, death, or property damage.
Never test for gas leaks with an open flame. Use a
commercially available soap solution made specifically
for the detection of leaks to check all connections. A fire
or explosion may result causing property damage, per-
sonal injury, or loss of life.
17. Check for gas leaks.
18. Replace main furnace door.
B. Secondary Heat Exchangers
NOTE: The condensing side (inside) of the secondary heat
exchangers CANNOT be serviced or inspected. A small number of
bottom outlet openings can be inspected by removing the inducer
assembly. See Flushing Collector Box and Drainage System
section for details on removing inducer assembly.
V. FLUSHING COLLECTOR BOX AND DRAINAGE
SYSTEM
1. Turn off gas and electrical supplies to furnace.
2. Remove main furnace door.
3. Disconnect inducer motor and pressure switch wires or
connectors.
4. Disconnect pressure switch tubes.
5. Disconnect vent pipe from inducer housing outlet by
loosening coupling clamp on inducer outlet.
6. Disconnect drain tube from inducer housing. (See Fig. 8.)
7. Remove inducer housing assembly by removing 4 bolts
attaching assembly to cell panel.
8. Flush inside of collector box with water until discharge
from condensate trap is clean and runs freely.
NOTE: Ensure the drain tube disconnected from the inducer
housing is higher than the collector box opening or water will flow
out tube.
9. Inspect inside area of collector box for any pieces of foreign
materials and remove if present.
CAUTION: UNIT DAMAGE HAZARD
DO NOT use wire brush or other sharp object to inspect
or dislodge materials in secondary heat exchangers as
failure of the secondary heat exchanger may occur. Flush
with water only.
10. Reassemble inducer assembly by reversing items 5-7.
Tighten the vent coupling clamp screw(s) to 15 in.-lb. of
torque.
Fig. 6—Cleaning Inlet Openings of Primary Heat
Exchangers
A96305
PRIMARY HX
INLET OPENINGS
Fig. 7—Combustion-Air Intake Housing Gasket Repair
A93087
PAM
RTV
—6—
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