Carrier 50HJ015-025, Installation, Start-Up And Service Instructions Manual

Page: 18 / 40

18
START-UP
Use the following information and Start-Up Checklist on
page CL-1 to check out unit PRIOR to start-up.
Unit Preparation —
Check that unit has been installed in
accordance with these installation instructions and all applica-
ble codes.
Compressor Mounting —
Compressors are internally
spring mounted. Do not loosen or remove compressor hold-
down bolts.
Refrigerant Service Ports —
Each refrigerant sys-
tem has a total of 3 Schrader-type service gage ports. One port
is located on the suction line, one on the compressor discharge
line, and one on the liquid line. In addition Schrader-type
valves are located underneath the low-pressure switches. Be
sure that caps on the ports are tight.
Compressor Rotation —
It is important to be certain
the compressors are rotating in the proper direction. To deter-
mine whether or not compressors are rotating in the proper
direction:
1. Connect service gages to suction and discharge pressure
fittings.
2. Energize the compressor.
3. The suction pressure should drop and the discharge pres-
sure should rise, as is normal on any start-up.
If the suction pressure does not drop and the discharge pres-
sure does not rise to normal levels:
1. Note that the evaporator fan is probably also rotating in
the wrong direction.
2. Turn off power to the unit.
3. Reverse any two of the incoming power leads.
4. Turn on power to the compressor.
The suction and discharge pressure levels should now move
to their normal start-up levels.
NOTE: When compressors are rotating in the wrong direction,
the unit will have increased noise levels and will not provide
heating and cooling.
After a few minutes of reverse operation, the scroll com-
pressor internal overload protection will open, which will acti-
vate the unit’s lockout and requires a manual reset. Reset is ac-
complished by turning the thermostat on and off.
Internal Wiring —
Check all electrical connections in
unit control boxes; tighten as required.
Crankcase Heater(s) —
Heater(s) is energized as long
as there is power to unit and compressor is not operating.
Evaporator Fan —
Fan belt and variable pulleys are fac-
tory installed. Remove tape from the fan pulley. See Table 8 for
Air Quantity Limits. See Tables 9-12 for Fan Performance
data. Be sure that fans rotate in the proper direction. See
Tables 13 and 14 for Static Pressure information for accesso-
ries and options. See Table 15 for fan rpm at various fan motor
pulley settings. See Table 16 for Evaporator-Fan Motor Speci-
fications. To alter fan performance, see Evaporator-Fan Perfor-
mance Adjustment section, page 27.
Table 8 — Air Quantity Limits
Condenser Fans and Motors —
Condenser fans and
motors are factory set. Refer to Condenser-Fan Adjustment
section (page 29) as required. Be sure that fans rotate in the
correct direction.
Return-Air Filters —
Check that correct filters are in-
stalled in filter tracks. See Table 1. Do not operate unit without
return-air filters.
Outdoor-Air Inlet Screens —
Outdoor-air inlet screens
must be in place before operating unit.
Accessory EconoMi$er Adjustment —
Remove
filter access panel. Check that outdoor-air damper blades are
closed and return-air damper blades are open.
EconoMi$er operation and adjustment is described in Base
Unit Operation and EconoMi$er Adjustment sections (this
page and page 29), respectively.
Base Unit Operation
COOLING, UNITS WITHOUT ECONOMI$ER — When
thermostat calls for cooling, terminals G and Y1 are energized.
The indoor (evaporator) fan contactor (IFC), and compressor
contactor no. 1 (C1) are energized and evaporator-fan motor,
compressor no. 1 and condenser fans start. The condenser-fan
motors run continuously while unit is cooling. If the thermostat
calls for a second stage of cooling by energizing Y2, compres-
sor contactor no. 2 (C2) is energized and compressor no. 2
starts.
HEATING, UNITS WITHOUT ECONOMI$ER (If Acces-
sory or Optional Heater is Installed) — Upon a call for heat-
ing through terminal W1, IFC and heater contactor no. 1 (HC1)
are energized. On units equipped for 2 stages of heat, when ad-
ditional heat is needed, HC2 is energized through W2.
COOLING UNITS WITH ECONOMI$ER — When the
OAT is above the ECON SP set point and the room thermostat
calls for Stage 1 cooling (R to G + Y1), the indoor-fan motors
(IFM) is energized and the EconoMi$er damper modulates to
minimum position. The compressor contactor and OFC are
energized to start the compressor and outdoor-fan motor
(OFM). After the thermostat is satisfied, the damper modulates
to the fully closed position when the IFM is deenergized.
When the OAT is below the ECON SP setting and the room
thermostat calls for Stage 1 cooling (R to G + Y1), the
EconoMi$er modulates to the minimum position when the
IFM is energized. The EconoMi$er provides Stage 1 of cooling
by modulating the return and outdoor air dampers to maintain a
55 F supply air set point. If the supply-air temperature (SAT) is
greater than 57 F, the EconoMi$er modulates open, allowing a
greater amount of outdoor air to enter the unit. If the SAT drops
below 53 F, the outdoor air damper modulates closed to reduce
the amount of outdoor air. When the SAT is between 53 and
57 F, the EconoMi$er maintains its position.
If outdoor air alone cannot satisfy the cooling requirements
of the conditioned space, and the OAT is above the MECH
CLG LOCKOUT set point, the EconoMi$er integrates free
cooling with mechanical cooling. This is accomplished by the
strategies below.
NOTE: Compressors have a two-minute Minimum On and
Minimum Off, which are accomplished by the strategies
below.
1. If Y1 is energized, and the room thermostat calls for Y2
(2-stage thermostat), the compressor and OFC are ener-
gized. The position of the EconoMi$er damper is main-
tained at its current value.
2. If Y1 is energized for more than 20 minutes, and Y2 is
not energized (whether or not a 2-stage thermostat is
used), the compressor and OFC are energized. The posi-
tion of the EconoMi$er damper is maintained at its cur-
rent value.
IMPORTANT: Unit power must be on for 24 hours prior
to start-up. Otherwise, damage to compressor may result.
UNIT
50HJ
MINIMUM CFM MAXIMUM CFM
015 3600 6,000
017
4500 7,500
025 6000 10,000