6
20
Filtering out trouble
A dirty filter will cause excessive stress on the furnace, heat
exchanger, and blower motor and can cause it to overheat
and automatically 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 match 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 location, 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. (See Fig. 11.)
21
22
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
efficiency.
!
!
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.)
23
5. Inspect the filter. If torn, replace the filter.
6. Wash the filter (if dirty) in a sink, bathtub, or outside
with a garden hose. Always use cold tap water. A mild
liquid detergent may be used if necessary. Spray water
through the filter in the opposite direction of airflow
through the cross-mesh binding (when present) side.
Allow filter to dry.
7. Reinstall the clean filter with the cross-mesh binding
(when present) side facing the furnace blower.
8. Put filter retainer back in the bracket opening and lock
it in place.
9. Replace blower and control access doors and turn on
electrical supply to the furnace. (See Fig. 23, 14, and
16.)
NOTE:
Two filters may be required in some upflow models
if side return ducts are used. The procedure listed above
may be used to remove side filters.
• Downflow/Horizontal Furnaces Only:
Two filters are located in the return-air plenum above the
blower (above line-of-sight) resting in the V-shaped channel
on top of the furnace. (See Fig. 24.)
1. Turn off electrical supply to the furnace. (See Fig. 19.)
2. Remove 2 screws from blower access door and remove
the door.
3. Remove the left-side filter by tipping the filter toward
the center and raising it from the V-shaped channel in
which it rests. (See Fig. 24 and 25.)
4. Lower filter down along side of the blower and remove
from the furnace.
5. To remove the right-side filter, lift from V-shaped chan-
nel and remove through left side the same way as left-
side filter.
6. Inspect the filter. If torn, replace the filter.
7. Wash the filter (if dirty) in a sink, bathtub, or outside
with a garden hose. Always use cold tap water. A mild
liquid detergent may be used if necessary. Spray water
through the filter in opposite direction of airflow
through the cross-mesh binding (when present) side.
Allow filter to dry.
8. Reinstall the clean filters with the cross-mesh binding
(when present) side facing the furnace blower.
