JOHNSON CONTROLS
93
SECTION 4 – MAINTENANCE
FORM 145.05-NOM7
ISSUE DATE: 10/31/2019
4
Sheave Alignment
To check sheave alignment, a straight edge or a piece of
string can be used. If the sheaves are properly aligned,
the string or straight edge touches at all points, as indi-
cated in
Rotating the sheaves
determines if the sheave is wobbly or the drive shaft is
bent. Alignment error must be corrected to avoid bear-
ing and belt failure.
Belts
New belts should be re-checked after 24 hours of op-
eration. On multiple belt adjustable pulleys, the pitch
depth should be checked to insure identical belt travel,
power transfer and wear. Adjustable motor bases are
provided for belt adjustment.
Motor pulleys and blower shaft pulleys are locked
in position with either set screws or split taper lock
bushings. All set screws and/or taper lock bolts must
be checked for tightness and alignment before putting
equipment into operation.
An incorrectly aligned and tensioned belt can substan-
tially shorten belt life or overload blower and motor
bearings, shortening their life expectancy. A belt ten-
sioned too tightly can overload the motor electrical,
causing nuisance tripping of the motor overloads and/
or motor failure and/or shaft failure.
Belt Replacement
Always replace belts as a set. Follow the steps below
to replace belts:
1. Release the tension on the belts by loosening the
adjusting nuts on the fan motor.
2. Remove old belts and recheck the sheave align-
ment with a straight edge.
3. Install the new belts on the sheaves.
FIGURE 60 -
SHEAVE ALIGNMENT
LD07634
CORD TOUCHING SHEAVES AT
POINTS INDICATED BY ARROWS
CORD TIED
TO SHAFT
Never place the belts on the sheaves by using a screw-
driver to pry the belt over the rim of the sheave. This
damages the belts permanently.
Belt Tensioning
A Browning Belt tension gauge is used in
properly tension belts.
FIGURE 61 -
BELT TENSIONING GAUGE
LD06354
Filter Drier Replacement
The filter drier should be replaced any time a refriger-
ant system is open. The unit comes with sealed (non-
replaceable) solid core driers. The filter driers are sized
for factory installation resulting in a smaller drier than
would normally be used in the field. When replacing
the drier in the field, select a replacement drier based
on the tonnage of the system and not the drier that was
shipped with the unit.
Supply Fan
In the unlikely event that the supply fan needs to be re-
placed the following procedure should to be followed:
1. The access panel to the right of the blower assem-
bly in the blower compartment allows access to
the rear bearing.
2. Thoroughly clean the shaft of all grease and rust
inhibitor. Be careful not to contaminate the bear-
ing grease. Use emery cloth to remove all rust or
the wheel may become “locked” to the shaft.
3. Loosen and remove the setscrews on both bearing
locking collars. Inspect and, if necessary, replace.