Harman® • PF-120 Owner’s Manual_R3 • 2014 -___ • 10/14
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3-90-08120c
G. Combustion Blower Chamber
Remove the combustion blower heat shield. There are two
latches that hold the shield in place. Figure 5.11. Flip the
latches up and pull the shield away from the furnace. It can
not be fully removed, it can only be moved down over the
wire until it hangs on the junction box.
The furnace
MUST be OFF and COOL
before you should
attempt to clean the combustion blower.
The wire to the combustion blower doesn’t need to be
disconnected during the cleaning process.
Loosen the three (3) thumb screws about 4 turns each. Figure
5.12. Hold the motor head with one hand and the blower
plate handle with the other hand. Pull outward on the plate
handle until the complete unit comes loose. Now rotate the
plate counter-clockwise about 1/8 turn. This will allow the
complete assembly to be removed from the blower chamber.
Clean the blower fan blades and the blower plate sealing
overlap. Figure 5.13.
Note:
Be careful not to bend the fan blades, this will throw
the fan blade out of balance or it may rub the inner chamber,
which may affect the performance of the furnace. Any
horizontal and vertical flue pipe directly above the unit should
be cleaned at this time.
Note:
The horizontal flue pipe directly above the furnace is
the first place fly ash will settle, due to the slowing of flue
gas velocity through horizontal pipe. Cleaning of horizontal
venting pipes is very important to the efficiency of this furnace.
Note:
Inspection, maintenance and cleaning of the
convection/distribution air filter should be done regularly.
H. Distribution Blower and Air Filter
Inspect and clean (if needed) the furnace cold air return
distribution blower and air filter located just below the
combustion blower chamber. This area should be inspected
monthly or more frequently depending on its installation
location. If the Air Filter is needing replaced use a 20”x20”x1”
Air Filter, Harman® part #3-40-20201-12.
Latch
Figure 5.11
Thumb Screws
Figure 5.12
Sealing Overlap
Figure 5.13
