11
b
earing
C
heCk
Prior to energizing any fans, check and make sure that all
setscrews are tight so that bearings are properly secured
to shafts.
For heat pump units, the airflow must be adjusted so that
the air temperature rise falls within the ranges given stated
on Data Plate (see Appendix A - Blower Performance).
s
et
e
vaPOratOr
f
an
r
Pm
Actual RPM’s must be set and verified with a tachometer or
strobe light. Refer to Appendices A and B for basic unit fan
RPM. Refer also to “Airflow” section of this manual. With
disconnect switch open, disconnect thermostat wires from
terminals Y and W. This will prevent heating and mechan-
ical cooling from coming on. Place a jumper wire across
terminals R and G at TB1 terminal block. Close disconnect
switch; evaporator fan motor will operate so RPM can be
checked.
t
ensiOn
and
a
lignment
a
djustment
Correct belt tension is very important to the life of your belt.
Too loose a belt will shorten its life; too tight, premature mo-
tor and bearing failure will occur. Check you belt drive for
adequate “run-in” belt tension by measuring the force re-
quired to deflect the belt at the midpoint of the span length.
Belt tension force can be measured using a belt tension
gauge, available through most belt drive manufacturers.
*Apply force to the center of the span.
t = Span length, inches
C = Center distance, inches
D = Larger sheave diameter, inches
d = Smaller sheave diameter, inches
h = Deflection height, inches
DRIVE BELT TENSION ADJUSTMENT
RECOMMENDED POUNDS OF FORCE PER BELT
SPAN LENGTH t
*DEFLECTION
FORCE
h
C
d
H
D
BELT
DRIVE
Used
New
A, AX Standard
3.0 to 4.0
4.2 ± .5 5.5 ± .5
0.313
DEFLECTION
(in)
DEFLECTION
FORCE (lbs)
SHEAVE
DIAMETER
(in)
TYPE
New V-belts will drop rapidly during the first few hours of
use. Check tension frequently during the first 24 hours of
operation. Tension should fall between the minimum and
maximum force. To determine the deflection distance from
a normal position, measure the distance from sheave to
sheave using a straightedge or a cord. This is your refer-
ence line. On multiple belt drives, an adjacent undeflected
belt can be used as a reference.
MOTOR SHEAVE ADJUSTMENTS
v
l
, v
m
, & 2
vP
v
ariable
P
itCh
k
ey
t
yPe
m
OtOr
s
heaves
The driving and driven motor sheaves should be in align-
ment with each other and the shafts parallel.
v
l
& v
m
s
heaves
a
djustment
1. Loosen set screw “B” using a 5/32” Allen key.
2. Making half or full turns from closed position, adjust
sheave pitch diameter for desired speed. DO NOT OPEN
MORE THAN FIVE FULL TURNS.
3. Tighten set screw “B” securely over flat.
4. Carefully put on belts and adjust belt tension. DO NOT
FORCE BELTS OVER GROOVES.
5. Ensure all keys are in place and the set screws tight be-
fore starting drive. Recheck set screws and belt tension
after 24 hours service.
NOTE:
Future adjustments should be made by loosening
the belt tension and increasing or decreasing the pitch di-
ameter of the sheave by half or full turns as required. Read-
just belt tension before starting drive.
SHEAVE DIAGRAM
NOTE:
Do not operate sheave with flange projecting be
-
yond the hub end.
r
efrigeratiOn
s
ystem
C
heCks
Ensure the hold-down bolts on the compressor are secure
and have not vibrated loose during shipment. Check that
the vibration grommets have been installed and visually
check all piping for damage and leaks and repair if nec-
essary. The entire system has been factory charged and
tested, making it unnecessary to field charge. Factory re
-
frigerant charge is shown on the unit’s nameplate.
C
B
VL & VM
