Page 49
17 - Remove electrical junction box from the side of the fur
nace.
18 - 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.
19 - Remove the primary limit from the vestibule panel.
20 - Remove two screws from the front cabinet flange at
the blower deck. Spread cabinet sides slightly to allow
clearance for removal of heat exchanger.
21 - Remove screws along vestibule sides and bottom
which secure vestibule panel and heat exchanger as
sembly to cabinet. Remove two screws from blower
rail which secure bottom heat exchanger flange. Re
move heat exchanger from furnace cabinet.
22 - Back wash heat exchanger with soapy water solution
or steam.
If steam is used it must be below 275°F
(135°C) .
23 - Thoroughly rinse and drain the heat exchanger. Soap
solutions can be corrosive. Take care to rinse entire
assembly.
24 - Reinstall heat exchanger into cabinet making sure that
the clamshells of the heat exchanger assembly is en
gaged properly into the support bracket on the blower
deck. Remove the indoor blower to view this area
through the blower opening.
25 - Re‐secure the supporting screws along the vestibule
sides and bottom to the cabinet.
26 - Reinstall cabinet screws on front flange at blower
deck.
27 - Reinstall the primary limit on the vestibule panel.
28 - Route heating component wiring through hole in blow
er deck and reinsert strain relief bushing.
29 - Reinstall electrical junction box.
30 - Reinstall the cold end header box.
31 - Reinstall the combustion air inducer. Reconnect the
plug to the wire harness.
32 - Reinstall pressure switches and reconnect pressure
switch wiring.
33 - Carefully connect combustion air pressure switch
tubing from pressure switches to proper ports on
cold end header collector box.
34 - Reconnect condensate drain line to the cold end
header box.
35 - Use securing screws to reinstall flue collar to the top
cap on the furnace. Reconnect exhaust piping and ex
haust drain tubing.
36 - Replace flexible exhaust adapter on combustion air in
ducer and flue collar. Secure using two existing hose
clamps.
37 - Reinstall burner box assembly in vestibule area. Se
cure burner box assembly to vestibule panel using
four existing screws.
Make sure burners line up in
center of burner ports
38 - Reconnect flame roll-out switch wires.
39 - Reconnect sensor wire and reconnect 2-pin plug from
ignitor.
40 - Reinstall gas valve manifold assembly. Reconnect
gas supply line to gas valve.
41 - Reconnect the combustion air intake pipe.
42 - Reinstall burner box cover.
43 - Reconnect wires to gas valve.
44 - Replace the blower compartment access panel.
45 - Reconnect gas supply piping. Turn on power and gas
supply to unit.
46- Follow lighting instructions on unit nameplate to light
and operate furnace for 5 minutes to ensure the fur
nace is operating properly.
47- Check all piping connections, factory and field, for gas
leaks. Use a leak detecting solution or other preferred
means.
48- Replace heating compartment access panel.
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.
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 wires 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 - Mark and disconnect sensor wire from the sensor. Dis
connect wires from flame rollout switches.
6 - Disconnect combustion air intake pipe. It may be nec
essary to cut the existing pipe to remove burner box
assembly.
7 - Remove four screws which secure burner box assem
bly to vest panel. Remove burner box from the unit.
8 - 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.
9 - Reinstall the burner box assembly using the existing
four screws. Make sure that the burners line up in the
center of the burner ports.
10 - Reconnect the sensor wire and reconnect the 2-pin
plug to the ignitor wiring harness. Reconnect wires to
flame rollout switches.
11 - Reinstall the gas valve manifold assembly. Reconnect
the gas supply line to the gas valve. Reinstall the burn
er box cover.
12 - Reconnect wires 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 heating compartment access panel.
