Service - Lennox ML180UHA Installation Instructions Manual

HEAT FAN‐OFF TIME IN SECONDS
NO JUMPER
To adjust fan-off timing, reposition jumper across pins to
achieve desired setting.
60 Second 90 Second
off Time off Time
FIGURE 28
NOTE - Do not secure the electrical conduit directly to the
air ducts or structure.
Electrical
1 - Check all wiring for loose connections.
2 - Check for the correct voltage at the furnace (furnace
operating). Correct voltage is 240VAC + 10%.
3 - Check amp-draw on the blower motor with inner blow­
er panel in place.
Unit Nameplate__________Actual__________
Blower Speeds
Follow the steps below to change the blower speeds.
1 - Turn off electrical power to furnace.
2 - Remove blower access panel.
3 - Disconnect existing speed tap at integrated control
speed terminal.
See unit Product Specifications bulletin for indoor blower
data.
NOTE - Termination of any unused motor leads must be
insulated.
4 - Place unused blower speed tap on integrated control
"PARK" terminal or insulate.
5 - Refer to blower speed selection chart on unit wiring dia­
gram for desired heating or cooling speed. See Blower
performance data beginning on the next page.
6 - Connect selected speed tap at integrated control
speed terminal.
7 - Resecure blower access panel.
8 - Turn on electrical power to furnace.
9 - Recheck temperature rise.
Electronic Ignition
The integrated control has an added feature of an internal
Watchguard control. The feature serves as an automatic re­
set device for integrated control lockout caused by ignition
failure. This type of lockout is usually due to low gas line
pressure. After one hour of continuous thermostat demand
for heat, the Watchguard will break and remake thermostat
demand to the furnace and automatically reset the integrat­
ed control to begin the ignition sequence.
120 Second 180 Second
off Time off Time
Page 22

Service

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, a qualified techni­
cian should check the system as follows:
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 ML180UHA filters are installed external to the unit. Fil­
ters should be inspected monthly. Clean or replace the fil­
ters when necessary to ensure that the furnace operates
properly. Replacement filters must be rated for high veloci­
ty airflow. Table 2 lists recommended filter sizes.
Flue And Chimney
1 - Check flue pipe, chimney and all connections for tight­
ness and to make sure there is no blockage.
2 - Check unit for proper draft.
Electrical
1 - Check all wiring for loose connections.
2 - Check for the correct voltage at the furnace (furnace
operating). Correct voltage is 240VAC + 10%.
3 - Check amp-draw on the blower motor with inner blow­
er panel in place.
Unit Nameplate__________Actual__________
Cleaning the Burners
NOTE - Use papers or protective covering in front of the fur­
nace during cleaning.
1 - Turn off both electrical and gas power supplies to fur­
nace.
2 - Label the wires from gas valve, rollout switches, prima­
ry limit switch and make-up box then disconnect them.