Lennox ML196DF045XE36B Manual page 46

Condensate Hose Screen (Figure 58)
Check the condensate hose screen for blockage and clean
if necessary.
1 - Turn off power to the unit.
2 - Remove hose from cold end header box. Twist and pull
screen to remove.
3 - Inspect screen and rinse with tap water if needed.
4 - Reinstall screen and turn on power to unit.
Condensate Hose Screen
FIGURE 58
Cleaning Heat Exchanger
If cleaning the heat exchanger becomes necessary, follow
the below procedures and refer to figure 1 when disassem­
bling unit. Use papers or protective covering in front of fur­
nace while removing heat exchanger assembly.
1 - Turn off electrical and gas supplies to the furnace.
2 - Remove the furnace access panels.
3 - Disconnect the wires from the gas valve.
4 - Remove gas supply line connected to gas valve. Re­
move the burner box cover (if equipped) and remove
gas valve/manifold assembly.
5 - Remove sensor wire from sensor. Disconnect 2‐pin
plug from the ignitor.
6 - Disconnect wires from flame roll-out switches.
7 - Loosen clamps at vent elbow. Disconnect condensate
drain tubing from flue collar. and remove the vent el­
bow.
8 - Loosen clamps and remove combustion air intake
flexible connector if equipped.
9 - Remove four burner box screws at the vestibule panel
and remove burner box. Set burner box assembly
aside.
NOTE - If necessary, clean burners at this time. Follow
procedures outlined in Burner Cleaning section.
10 - Mark and disconnect all combustion air pressure tub­
ing from cold end header collector box.
11 - Mark and remove wires from pressure switch assem­
bly. Remove pressure switch assembly. Keep tubing
attached to pressure switch assembly.
12 - Disconnect the plug from the combustion air inducer.
Remove two screws which secure combustion air in­
ducer to collector box. Remove combustion air induc­
er assembly. Remove ground wire from vest panel.
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.
Hose
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.
Page 46