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6
necessary adjustments to operate
the blower at either the low- or
high-heat speed.
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NOTE:
If the burners fail to ignite after
4 attempts, the furnace control system
will lock out. If lockout occurs, main
burners fail to light, or blower does not
come on, shut down the furnace and
call your dealer for service.
12. Set your thermostat to the temper-
ature that satisfies your comfort
requirements.
SUGGESTION: Setting the ther-
mostat back a few degrees and
compensating for the difference
with warmer clothing can make a
big difference in your fuel con-
sumption. The few degrees at the top
of your thermostat “comfort level”
are the most costly degrees to obtain.
O
P
E
N
When room temperature drops
below the temperature selected
on the thermostat, the furnace
will be switched on automatically.
When room temperature reaches
the temperature selected on the
thermostat, the furnace will be
switched off automatically.
Some thermostats have a FAN
mode with 2 selections, AUTO
and ON. When thermostat is set
to AUTO, the furnace blower
cycles on and off. In ON mode, the
furnace blower runs continu-
ously. Continuous fan keeps the
temperature level in your home
more evenly balanced. It also per-
mits the indoor air to be continu-
ously filtered. Fan On
Plus
™ –On
all but the 340MAV, the blower
speed can be increased or
decreased if desired due to change
of seasons, large gatherings in
your home, etc. Simply change
your FAN from ON to OFF (or
AUTO depending on your thermo-
stat), and then return to ON. The
blower will switch to the next
highest speed. There are at least 3
speeds to choose from. If the
blower is running on its highest
speed, a request to change will
direct the blower to return to its
lowest speed.
SHUTTING DOWN
YOUR FURNACE
Should you need to shut down your
furnace for service or maintenance,
you will need to turn the furnace off.
The following procedures must be
followed:
1. Set your room thermostat to the
lowest temperature setting.
(See Fig. 19.)
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2. Close the external manual gas
valve. (See Fig. 9.)
3. Turn off electrical supply to the
furnace. (See Fig. 20.)
4. Remove main furnace door.
(See Fig. 11.)
5. Turn switch on the gas valve to
OFF position.
(See Fig. 21 or 22.)
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6. Replace main furnace door.
(See Fig. 16.)
7. If the furnace is being shut down
because of a malfunction, call
your dealer as soon as possible.
PERFORMING
ROUTINE
MAINTENANCE
NOTE:
The qualified installer or
agency must use only factory-
authorized replacement parts, kits,
and accessories when modifying this
product.
®
CAUTION
Furnace is not to be installed,
operated, and then turned off
and left turned off in an unoc-
cupied structure during winter.
(See “Heading South for the
Winter?” procedures in main-
tenance section on page 9.)
Freeze damage to furnace
would occur.
For 352MAV and 355MAV
ON
OFF
For 340MAV and 350MAV
or
!