TM 5-4520-240-14
p. Remove the shock mounts (4) from the blower
parts.
housing (5), and pull off the blower housing to remove
d. Inspect the blower housing, fan and tube, back
it. Loosen the setscrew (6) in the outer impeller (7), and
plate, and motor mount for distortion, broken welds,
remove the impeller from the motor shaft. Pull off the
and other damage. Replace defective parts.
fan and tube (8).
e. Remove and inspect the motor brushes for cracks,
q. Loosen the setscrew (9) securing the inner impeller
chips, wear, or scoring. Replace brushes if damaged or
(10) to the motor shaft, and remove the impeller.
if they are worn to less than 5/16 inch.
Remove the two nuts (11) and lock washers (12) secur-
f. Inspect the condition of the motor commutator.
ing the back plate (13) to the motor, and remove the
Replace the motor if the commutator is scored or badly
back plate.
burned. Light scoring of the commutator can be
r. Loosen the nuts (14) and back out the screws (15)
cleaned up using fine sandpaper.
securing the motor assembly to the motor mount (16).
g. Visually inspect the motor armature and stator for
Slide out the motor to remove it.
signs of overheating or other damage. Inspect the bear-
s. Loosen the setscrew (17) securing the fan (18) to the
ings for wear and scoring. Replace defective motor
motor shaft, and remove the fan. Remove the brush
parts.
caps (19) and brushes (20).
h. Inspect the suppression capacitor for burned or
t. If the suppression capacitor (37) or the motor is
broken insulation or other damage. If a capacitance
faulty, disassemble the motor as follows:
tester is available, test the capacitor. Capacitance
(1) Remove the nuts (21) and lock washers (22) that
should be 0.47 microfarad. If a capacitance tester is not
secure the end bell (23) to the motor assembly; remove
available, test the capacitor for continuity with an
the end bell.
ohmmeter. Replace the suppression capacitor if the
(2) Remove the spring washer (25) and shims (26
ohmmeter indicates that it is shorted, or if the capaci-
and 27), and retain them for reassembly, Pull the ar-
tance tester indicates it is defective.
mature (28) from the stator (30).
i. Discard and replace the sealing tape (1) and
(3) Separate the stator (30) from the commutator
gaskets (2 and 3). Replace the shock mounts (4) if they
end bell (38) to provide access to the capacitor mount-
are worn or damaged.
ing hardware.
10-4. Reassembly and Installation.
(4) Slide the plastic tie (31) from the capacitor to
a. Reassemble the motor and blower assembly in the
release the lead. Remove the tape (32) and insulator (33)
reverse order of the index numbers in figure 10-4. Be
from the suppression capacitor (37). Unsolder the
sure to use new gaskets.
electrical lead from the capacitor terminal inside the
b. When reassembling, check that impellers (7 and
motor. Remove the nut (35) and lock washer (36), and
10) and fan (18) are positioned on the motor shaft to
remove the capacitor (37) from the end bell.
prevent scraping or binding against related parts.
10-3. Cleaning and Inspection.
c. Line up the alignment marks on the back plate
WARNING
(13), fan and tube (8), and blower housing (5) before
sealing the assembled blower with tape (l).
Clean parts in a well-ventilated area.
d. Use rosin-core solder when soldering the lead to
Avoid inhalation of solvent fumes and
the suppression capacitor (37).
prolonged exposure of skin to cleaning
e. Install the blower assembly in the heater case as
solvent. Wash exposed skin
shown in figure 10-3. Secure with attaching screws (25)
thoroughly. Dry cleaning solvent (fed.
and lock washers (26).
spec. P-D-680) used to clean parts is
f. Connect the white-black lead to the ground ter-
potentially dangerous to personnel
minal of the motor. Connect the gray lead to the plug-in
and property. Do not use near open
connector as shown in the wiring diagram (fig. 1-4).
flame or excessive heat. Flash point of
Connect the motor ground strap to the fuel pump
solvent is 100F (38C).
mounting stud, and secure it with the attaching nut
a. Wipe the exterior of the motor assembly with a
and lock washer.
cloth dampened with dry cleaning solvent (fed. spec. P-
g. Install the heat exchanger and burner head in the
D-680). Prevent solvent from entering the motor. Clean
heater case in the reverse order of the index numbers in
he motor stator and armature using clean, dry, low
pressure (30 psi maximum) compressed air to blow out
h.Install the thermocouple in the heat exchanger
dust and dirt. Wipe off any grease with a cloth dam-
using a new grommet (11, fig. 10-2). Install the glow
pened with solvent.
plug, igniter, and combustion air hose in the reverse
b. Clean metal parts in dry cleaning solvent and
order of the index numbers in figure 10-2.
allow to dry thoroughly before reassembly.
i. Install the carburetor in the burner head in the
c. Inspect the impellers and the fan for bent or
reverse order of the index numbers in figure 10-1.
broken blades or other damage. Replace damaged
10-5
