Carrier 50HJ015 - Start-Up

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
applicable codes.
Compressor Mounting — Loosen compressor hold¬
down bolts until sideways movement of the washer
under each holddown bolt head can be obtained. Do not
loosen completely, as bolts are self-locking and will main¬
tain adjustment.
Internal Wiring — Check all electrical connections in
unit control boxes; tighten as required.
Refrigerant Service Ports and Valves — Each 50HJ
unit has 2 Schrader-type service ports per circuit; one on
the suction line and one on the liquid line. Be sure that the
caps on the ports are tight. The units also have 2 service
valves per circuit; one on the suction line and one on the
discharge line. Be sure all valves are open.
Crankcase Heaters — Heaters are energized as long
as there is power to unit.
IMPORTANT: Unit power must be on for 24 hours
prior to start-up. Otherwise, damage to compressor
may result.
Evaporator Fan — Fan belt and pulleys are factory in¬
stalled. Remove tape from the fan pulley and adjust pulleys
on 50HJ015 units as required. See Evaporator-Fan Perfor¬
mance Adjustment section on page 12. See Table 4 for Air
Quantity Limits. See Tables 5, 6A, and 6B for Fan Perfor¬
mance data. Be sure that fans rotate in the proper direction.
See Table 7 for Static Pressure Drops for accessories and
options. To alter fan performance, see Evaporator-Fan Per¬
formance Adjustment sections, pages 12 and 13.
Table 4 — Air Quantity Limits
UNIT 50HJ MINIMUM CFM
MAXIMUM CFM
015 3750 6,250
024
6000 10,000
Condenser Fans and Motors — Fans and motors
are factory set. Refer to Service, Condenser-Fan Adjust¬
ment section as required.
Return-Air Filters — Check that correct filters are
installed 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 Field-Installed Economizer Adjust¬
ment — Remove filter access panel. Check that outdoor-
air damper is closed and return-air damper is open.
Economizer operation and adjustment is described in
Start-Up, Base Unit Operation; and Service, Economizer
Adjustment sections, respectively.
Base Unit Operation
COOLING, UNITS WITHOUT ECONOMIZER - When
thermostat calls for cooling, terminals G and Y1 are ener¬
gized. The indoor (evaporator) fan contactor (IFC) and com¬
pressor contactor no. 1 (Cl) are energized and evaporator-
fan motor, compressor no. 1 (024) or unloaded compressor
(015), 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, compressor
contactor no. 2 (C2) is energized and compressor no. 2 starts
(024), or compressor no. 1 runs fully loaded (015).
A freeze protection thermostat (FPT) is located on the
evaporator coil. It detects frost buildup and turns off the
compressors, allowing the coil to clear. Once frost has melted,
the compressors can be reenergized by resetting the
thermostat.
HEATING, UNITS WITHOUT ECONOMIZER (If Acces¬
sory or Optional Heater is Installed) — Upon a call for
heating through terminal Wl, IFC and heater contactor
no. 1 (HC1) are energized. On units equipped for 2 stages
of heat, when additional heat is needed, HC2 is energized
through W2.
COOLING, UNITS WITH ECONOMIZER - Upon a call
for cooling, when outdoor ambient temperature is above the
outdoor-air temperature control setting, the evaporator and
condenser fans and compressor energize. The economizer
damper moves to VENT position.
Upon a first-stage call for cooling, when outdoor ambi¬
ent temperature is below the temperature control setting,
the evaporator fan starts and economizer damper modulates
to maintain mixed-air temperature. The compressor(s) re¬
mains off.
Upon a second-stage call for cooling, compressor no 1
(024) or unloaded compressor (015) is energized and me¬
chanical cooling is integrated with economizer cooling Com¬
pressor no. 2 (024 only) is locked out. If the outdoor-air
temperature is below 50 F, a cooling lockout switch
prevents the compressor(s) from running.
When supply-air temperature drops below a fixed set point,
the economizer damper modulates to maintain the temper¬
ature at the fixed set point.
HEATING, UNITS WITH ECONOMIZER (If Accessory
or Optional Heater is Installed) — The outdoor air damper
stays at VENT position while the evaporator fan is operat¬
ing Upon a call for heating through terminal Wl, the in¬
door (evaporator) fan contactor (IFC) and heater contactor
no. 1 (HC1) are energized. On units equipped for 2 stages
of heat, when additional heat is needed, HC2 is energized
through W2.
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