Maintenance - Lennox ML193UH045P36B Unit Information

VI−MAINTENANCE
WARNING
ELECTRICAL SHOCK, FIRE,
OR EXPLOSION HAZARD.
Failure to follow safety warnings exactly could result
in dangerous operation, serious injury, death or
property damage.
Improper servicing could result in dangerous opera-
tion, serious injury, death, or property damage.
Before servicing, disconnect all electrical power to
furnace.
When servicing controls, label all wires prior to dis-
connecting. Take care to reconnect wires correctly.
Verify proper operation after servicing.
At the beginning of each heating season, system should be
checked as follows by a qualified service technician:
Blower
Check the blower wheel for debris and clean if necessary.
The blower motors are prelubricated for extended bearing
life. No further lubrication is needed.
WARNING
The blower access panel must be securely in place
when the blower and burners are operating. Gas
fumes, which could contain carbon monoxide, can
be drawn into living space resulting in personal inju-
ry or death.
Filters
All air filters are installed external to the unit. Filters should
be inspected monthly. Clean or replace the filters when
necessary to ensure proper furnace operation. Table 17
lists recommended filter sizes.
TABLE 17
Furnace
Cabinet Width
Side Return
17−1/2" 16 X 25 X 1 (1)
21" 16 X 25 X 1 (1)
24−1/2" 16 X 25 X 1 (2)
Exhaust and air intake pipes
Check the exhaust and air intake pipes and all connections
for tightness and to make sure there is no blockage.
NOTE − After any heavy snow, ice or frozen fog event the
furnace vent pipes may become restricted. Always check
the vent system and remove any snow or ice that may be
obstructing the plastic intake or exhaust pipes.
Electrical
1 − Check all wiring for loose connections.
2 − Check for the correct voltage at the furnace (furnace
operating). Correct voltage is 120VAC + 10%
Filter Size
Bottom Return
16 X 25 X 1 (1)
20 X 25 X 1 (1)
24 X 25 X 1 (1)
Page 39
3 − Check amp−draw on the blower motor with blower ac-
cess panel in place.
Motor Nameplate__________Actual__________
Winterizing and Condensate Trap Care
1 − Turn off power to the furnace.
2 − Have a shallow pan ready to empty condensate water.
3 − Remove the clean out cap from the condensate trap
and empty water. Inspect the trap then reinstall the
clean out cap.
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 burner access panel.
3 − Mark all gas valve wires and disconnect them from
valve.
4 − Remove gas supply line connected to gas valve.
5 − Remove sensor wire from flame sensor. Disconnect
2-pin plug from the ignitor.
6 − Disconnect wires from flame roll−out switches.
7 − Remove four burner assembly screws at the vestibule
panel and remove gas valve /manifold and burner box
as a single unit.
NOTE − If necessary, clean burners at this time. Follow
procedures outlined in Burner Cleaning section.
9 − Remove the clean−out cap on trap and drain. Replace
cap.
10 − Disconnect condensate drain line from the conden-
sate trap. Remove condensate trap (it may be neces-
sary to cut drain pipe). Remove the 1/2" NPT fitting
from the cold end header box. Disconnect drain tubes
from cold end header collector box.
11 − Disconnect condensate drain tubes from flue collar.
Remove screws that secures flue collar in place. Re-
move flue collar. It may be necessary to cut the exiting
exhaust pipe for removal of the fitting.
12 − Loosen two clamps from flexible no−hub exhaust col-
lar.
13 − Disconnect the 2-pin plug from the combustion air in-
ducer. Remove screws which secure combustion air
inducer to collector box. Remove combustion air in-
ducer assembly. Remove ground wire.
14 − Mark and disconnect all combustion air pressure tub-
ing from cold end header collector box.
15 − Mark and remove wires from pressure switch. Re-
move pressure switch. Keep tubing attached to pres-
sure switch.
16 − Remove electrical junction box from the side of the fur-
nace.
17 − Remove blower access panel.
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.