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13 − Remove electrical junction box from the side of the fur-
nace.
14 − Disconnect condensate line from cold end header
box. Remove cold end header box.
15 − Loosen clamps on exhaust and air intake pipe seal
plate. Slide exhaust and intake pipes up and out to
clear blower deck. Remove exhaust and air intake
pipe seal plate.
16 − Mark and disconnect any remaining wiring to heating
compartment components. Disengage strain relief
bushing and pull wiring and bushing through the hole in
the blower deck.
17 − Remove the primary limit from the vestibule panel.
18 − Remove two screws from the front cabinet flange at
the blower deck. Spread cabinet sides slightly to allow
clearance for removal of heat exchanger.
19 − Remove screws along vestibule sides which secure
vestibule panel and heat exchanger assembly to cabi-
net. Remove two screws from blower rail which secure
top heat exchanger flange. Remove heat exchanger
from furnace cabinet.
20 − Back wash heat exchanger with soapy water solution
or steam.
If steam is used it must be below 275°F
(135°C) .
21 − Thoroughly rinse and drain the heat exchanger. Soap
solutions can be corrosive. Take care to rinse entire
assembly.
22 − Reinstall heat exchanger into cabinet making sure that
the clamshells of the heat exchanger assembly are
engaged properly into the support bracket on the
blower deck. Remove the indoor blower to view this
area through the blower opening.
23 − Re-secure the supporting screws along the vestibule
sides and top to the cabinet.
24 − Reinstall cabinet screws on front flange at blower
deck.
25 − Reinstall the primary limit on the vestibule panel.
26 − Route heating component wiring through hole in blow-
er deck and reinsert strain relief bushing.
27 − Reinstall electrical junction box.
28 − Reinstall exhaust and air intake pipe seal plate. Rein-
stall exhaust and air intake pipes and tighten clamps
on pipe seal plate.
29 − Reinstall the cold end header box.
30 − Reinstall the combustion air inducer. Reconnect the
combustion air inducer to the wire harness.
31 − Reinstall pressure switch assembly and reconnect
pressure switch wiring.
32 − Carefully connect combustion air pressure switch
tubing from pressure switches to proper ports on
cold end header collector box.
33 − Reinstall condensate trap.
34 − Secure burner box assembly to vestibule panel using
four existing screws.
Make sure burners line up in
center of burner ports.
35 − Reconnect exhaust piping and exhaust drain tubing.
36 − Reconnect flame roll−out switch wires.
37 − Reconnect sensor wire and reconnect 2−pin plug from
ignitor.
38 − Reinstall gas valve manifold assembly. Reconnect
gas supply line to gas valve.
39 − Reinstall burner box cover if equipped.
40 − Reconnect plug to gas valve.
41 − Replace the blower compartment access panel.
42 − Follow lighting instructions on unit nameplate to light
and operate furnace for 5 minutes to ensure the fur-
nace is operating properly.
43− Check all piping connections, factory and field, for gas
leaks. Use a leak detecting solution or other preferred
means.
CAUTION
Some soaps used for leak detection are corrosive to
certain metals. Carefully rinse piping thoroughly af-
ter leak test has been completed. Do not use
matches, candles, flame or other sources of ignition
to check for gas leaks.
44 − Replace access panel.
Cleaning the Burner Assembly (if needed)
1 − Turn off electrical and gas power supplies to furnace.
Remove upper and lower furnace access panels.
2 − Disconnect the 2−pin plug from the gas valve.
3 − Remove the burner box cover (if equipped).
4 − Disconnect the gas supply line from the gas valve. Re-
move gas valve/manifold assembly.
5 − −Loosen clamps and remove combustion air intake
flexible connector (if equipped).
5 − Mark and disconnect sensor wire from the sensor. Dis-
connect plug from the ignitor at the burner box.
6 − Remove four screws which secure burner box assem-
bly to vest panel. Remove burner box from the unit.
7 − Use the soft brush attachment on a vacuum cleaner to
gently clean the face of the burners. Visually inspect
the inside of the burners and crossovers for any block-
age caused by foreign matter. Remove any blockage.
8 − Reinstall the burner box assembly using the existing
four screws. Make sure that the burners line up in the
center of the burner ports.
9 − Reconnect the sensor wire and reconnect the 2−pin
plug to the ignitor wiring harness.
10 − Reinstall combustion air intake flexible connector (if
equipped), secure using existing clamps.
11 − Reinstall the gas valve manifold assembly. Reconnect
the gas supply line to the gas valve. Reinstall the burn-
er box cover.
12 − Reconnect plug to gas valve.
13 − Replace the blower compartment access panel.
14 − Refer to instruction on verifying gas and electrical con-
nections when re−establishing supplies.
15 − Follow lighting instructions to light and operate fur-
nace for 5 minutes to ensure that heat exchanger is
clean and dry and that furnace is operating properly.
16 − Replace access panel.
