11
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 mechanical 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 motor and
bearing failure will occur. Check you belt drive for adequate
“
run-
in” belt tension by measuring the force required 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.
SPAN LENGTH t
*DEFLECTION
FORCE
h
C
d
H
D
*
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
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
RECOMMENDED POUNDS OF FORCE PER BELT
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, mea-
sure the distance from sheave to sheave using a straightedge or a
cord. This is your reference line. On multiple belt drives, an adja-
cent 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 alignment 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 before
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 diameter of the
sheave by half or full turns as required. Readjust belt tension before
starting drive.
C
B
VL & VM
SHEAVE DIAGRAM
NOTE:
Do not operate sheave with flange projecting beyond the
hub end.
R
EFRIGERATION
S
YSTEM
C
HECKS
This unit is equipped with a piston type metering device.
Ensure the hold-down bolts on the compressor are secure and have
not vibrated loose during shipment. Check that the vibration grom-
mets have been installed and visually check all piping for damage
and leaks and repair if necessary. The entire system has been fac-
tory charged and tested, making it unnecessary to field charge.
Factory refrigerant charge is shown on the unit’s nameplate.
To confirm charge levels or, if a leak occurs and charge needs to be
added to the system, it is recommended to evacuate the system
and recharge refrigerant to the unit’s nameplate specifications.
This unit has been rated in the cooling mode at the AHRI rated
conditions of: indoor (80°F db/67°F wb) and outdoor (95°F db).
While operating at this condition, the superheat should range from
9°F to 11°F for each refrigeration circuit measured at the suction
service port located near the compressor.
S
TART
-U
P
P
ROCEDURE
AND
C
HECKLIST
Begin with power turned off at all disconnects.
A
IR
C
ONDITIONING
S
TART
-U
P
P
ROCEDURE
1. Turn thermostat system switch to
“
Cool,” and fan switch
