Carrier 38AH044-134 - Manual (Page 37)

Table 15 — Main Power Connection and Control Circuit Wiring
MAIN POWER CONNECTION CONTROL CIRCUIT
Electrical
Characteristics
(V-Ph-Hz)
Qty
Terminal
Blocks
Qty
Parallel
Conductors*
Max Wire
Size
(kcmil)
Control Power
(V)
Safety Circuit
(V)
208/230-3-60 1 6 500 115f 24
460-3-60
575-3-60
1 3 500 115t 24
230-3-50 1 6 500 230 24
380-3-60
380/415-3-50
1 3 500 230 24
346-3-50 1 3 500 200 24
LEGEND
kcmil — Thousand Circular Mils
‘Conductors are from the safety disconnect.
tControl power is accomplished with a step-down transformer where primary voltage is field voltage
Step 5 — Install Accessories
LOW-AMBIENT OPERATION
Units 38AH044-084. 124, and 134 — If operating tempera­
tures below 55 E (13 C) are expected, Motormaster® III fan
motor control is recommended. Refer to separate installa­
tion instructions for low-ambient operation guidelines.
Units 38AH094 and 104 — If operating temperatures below
45 F (7 C) are expected, Motormaster III fan motor control
is recommended. Refer to separate installation instructions
for low-ambient operation guidelines.
MISCELLANEOUS ACCESSORIES — For applications re­
quiring special accessories, the following packages are avail­
able; condenser coil hail guard package, gage panel, unloader
package, unloader conversion kits, sound reduction pack­
age, condenser coil protective grilles, compressor security
grilles, ModuPaneFM control, and thermostat transformer re­
lay package.
PRE-START-UP
IMPORTANT: Before beginning Pre-Start-Up or Start-
Up, review Start-Up Checklist at the back of this pub­
lication. The Checklist assures proper start-up of a unit
and provides a record of unit condition, application re­
quirements, system information, and operation at ini­
tial start-up.
Do not attempt to start the air-conditioning system until
following checks have been completed.
System Check
1. Check all system components, including the air­
handling equipment. Consult manufacturer’s instruc­
tions. If the unit has field-installed accessories, be sure
all are properly installed and wired correctly. Refer to
unit wiring diagrams.
2. Backseat (open) compressor suction and discharge shut­
off valves. Close valves one turn to allow refrigerant pres­
sure to reach the test gages.
3. Open liquid line service valves.
4. Check tightness of all electrical connections.
5. Oil should be visible in the compressor sight glasses.
See Fig. 29. An acceptable oil level in the compressor
is from Vs to Vs of sight glass. Adjust the oil level as
required. No oil should be removed unless the crank­
case heater has been energized for at least 24 hours. See
Start-Up section on page 38, Preliminary Oil Charge,
for Carrier-approved oils.
6. Electrical power source must agree with unit
nameplate.
A CAUTION
Crankcase heaters on all units are wired into the control
circuit, so they are always operable as long as the main
power supply disconnect is on (closed), even if any safety
device is open. Compressor heaters must be on for 24
hours prior to the start-up of any compressor.
7. Crankcase heaters must be firmly locked into compres­
sors, and must be on for 24 hours prior to start-up.
8. Fan motors are 3-phase. Check rotation of fans during
first start-np check. Fan rotation is clockwise as viewed
from top of unit. If fan is not turning clockwise, reverse
2 of the power wires.
9. Check compressor suspension. On units 38AH044-084,
124, and 134, snubber washers (for noise suppression)
can be moved with finger pressure. On units 38AH094
and 104, rails allow compressors to float freely on com­
pressor rail springs.
10. On 38AH074,084 single-circuit units and Modnle
38AH134B, ensure that the packaging block located be­
tween the oil eqnalization tube and the compressor cross­
brace has been removed.
START-UP
Compressor crankcase heaters must be on for 24 hours
before start-up. To energize the crankcase heaters, set the
space thermostat above the ambient so there will be no de­
mand for cooling. Close the field disconnect and turn on the
fan circuit breakers. Leave the compressor circuit breakers
off/open. The crankcase heaters are now energized.
37