PREVOST LE MIRAGE XLII BUS SHELLS, Maintenance Manual

Page: 1093 / 1260

Section 22: HEATING AND AIR CONDITIONING
PA1564
25
CAUTION
If grinding with a honing stone, you must
disconnect the time delay in order to keep the
motor in 1
st
speed. If you prefer, you may also
install a jumper on the evaporator motor
between terminal E2 and A1 to bypass relay
R60 and keep the motor in 1
st
speed as well.
b) Grinding with the honing stone is always
done under reduced voltage. Dust particles
act like abrasive and wear down the brushes
exactly with the profile of the commutator.
Caution is advised here as prolonged
honing could wear the brushes and
commutator prematurely.
FIGURE 28: GRINDING WITH THE BRUSH SEATER
STONE
22319
Repeat method a or b until brushes are fully
seated.
Seating surface of the brush must be
no less than 80% of the face (Refer to figure
29).
FIGURE 29: SEATING SURFACE OF THE BRUSH
22320
CAUTION
After grinding with the sandpaper or the
honing stone, it is necessary to remove the
brushes from the brush holders and
vigorously clean with an air gun the
commutator and the seating faces of the
brushes to eliminate abrasive dust and dust
from brushes.
DANGER
Use a dust mask to prevent inhalation of dust
particles. Protect against electrical shock
when working on energized equipment.
Protect against falling or slipping when
working on rotating equipment.
CAUTION
If grinding is not carried out or is carried out in
an incorrect way, the brush may seat against
a restricted zone only, which will create a high
amperage situation for the commutator as for
the brushes and could seriously damage the
motor.
After grinding is completed, it is necessary to
check the evaporator motor amperage in 1
st
speed and in 2
nd
speed. Make sure that the
evaporator compartment door is closed and
that the reading is
30 A ± 3 in 1
st
speed.
Confirm that the reading is 64 A ± 4 (MAX 68
A) in 2
nd
speed.
9.3.6 Brush Holder Adjustment
NOTE
The brush holders are mounted on a support
that can rotate. Rotating that rocker ring will
move all the brush holders at the same time.
1. Remove the screws securing the grid and
remove the grid. Locate the 2 bolts fixing the
mechanism permitting the rotation of the
brush rocker ring.
2. Loosen (do not remove) the bolts just
enough to release the mechanism.
3. Move gently the exposed brush holder in
order to have 30 A ± 3 in 1
st
speed and 64
A ± 4 in 2
nd
speed when the door is
closed and a maximum distance of 10 mm