6
switched on automatically. When the room temperature
reaches the degree selected on the thermostat, the furnace
will be automatically switched off.
Some thermostats have a “fan” switch with 2 selections:
AUTO or ON. When set on AUTO, the furnace blower
cycles on and off, controlled by the thermostat. In the ON
position, the furnace blower runs continuously except for
a 45-sec delay at the “call for heat.” This keeps the tem-
perature level in your home more evenly balanced. It also
continuously filters the indoor air.
Shutting down your furnace
Should you ever suspect a malfunction in your furnace,
you will need to turn the furnace off. The following pro-
cedures must be followed:
1. Set your room thermostat to the lowest temperature
setting. (See Fig. 18.)
2. Close the external manual gas valve. (See Fig. 8 on
page 5.)
3. Turn OFF the electrical power to your furnace. (See
Fig. 19.)
18 19
4. Remove the control access door on your furnace. (See
Fig. 10 or 11.) On upflow furnaces, removing the
blower access door is not required.
5. Turn the control knob on the gas valve to the OFF
position. (See Fig. 20.)
6. Replace the control access door. (See Fig. 14 or 15.)
7. If the furnace is being shut down because of a mal-
function, call your dealer as soon as possible.
Performing routine maintenance
With the proper maintenance and care, your furnace will
operate economically and dependably. Basic mainte-
nance, which can easily be accomplished by someone who
follows the directions, is found on this and the following
pages. However, before beginning maintenance, follow
these safety precautions:
20
SYSTEM
COOL
OFF
HEAT
FAN
AUTO
ON
50
70
90
50
70
90
Filtering out trouble
A dirty filter will cause excessive stress on the furnace
blower motor and can cause it to overheat and automati-
cally shut down. The furnace filter should be checked
every 3 or 4 weeks and cleaned if necessary.
If your furnace filter needs replacing, be sure to use the
same size and type of filter that was originally supplied.
Use the Furnace Filter Table and compare your furnace
size with the proper filter size.
The air filter for upflow furnaces is normally located in the
blower compartment. Filters for the downflow furnaces
are normally located in the return air plenum above the
blower. If the filters have been installed in another loca-
tion, contact your dealer for instructions. To inspect, clean
and/or replace the air filter(s), follow these steps:
• Upflow Furnaces Only:
1. Turn OFF the electrical supply to the furnace. (See
Fig. 19.)
2. Remove control and blower access doors.
21 22
3. Push filter retainer toward the bracket opening to
release the filter. (See Fig. 21.)
4. Gently remove the filter and carefully turn the dirty
side up (if dirty) to avoid “spilling” dirt from the filter.
(See Fig. 22.)
WARNING
Turn off electrical power supply to your furnace
before removing the access doors to service or
perform maintenance. A failure to follow this
warning could result in personal injury or death.
CAUTION
Although special care has been taken to minimize
sharp edges, be extremely careful when handling
parts or reaching into the furnace.
CAUTION
Never operate your furnace without a filter in
place. Doing so may damage the furnace blower
motor. An accumulation of dust and lint on inter-
nal parts of your furnace can cause a loss of effi-
ciency.
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