Carrier 48TJ016-028 - Manual (Page 31)

CONDENSER CO!L
SUCTION
S-LPS
SUB COOLER CONTROL
LOW PRESSURE SWITCH
EQUALIZER LINE
TXV — Thermostatic Expansion Valve
Fig. 45 — MoistureMiSer’^“ Dehumidification Package Operation Diagram
START-UP
Use the following infoniiation and Stait-Up Checklist on
page CL-1 to check out unit PRIOR to stait-up.
Unit Preparation — Check that unit has been installed in
accordance with these installation instinctions and all applica­
ble codes.
COMPRESSOR MOUNTING — Do not loosen or remove
compressor holddown bolts.
REFRIGERANT SERVICE PORTS — Each refrigerant sys­
tem has a total of 3 Schrader-type service gage ports. One port
is located on tlie suction line, one on the compressor discharge
line, and one on the liquid line. In addition Schrader-type
valves are located underneath tlie low-pressure switches. Be
sure that caps on the ports are tight.
COMPRESSOR ROTATION
48TJ016 and 020 Only — The unit is equipped with a Phase
Monitor Relay (PMR) board located in the control box. The
PMR device will not allow the unit to nm if field power is con­
nected incorrectly. To determine if the Phase Monitor Relay is
preventing the unit from starting, check to see if the red LED is
blinking. If tlie LED is blinking, the 3-phase field power has
been wired incorrectly. A solid light means that field power
connections are correct.
48TJ024 and 028 Only — It is important to be certain the
compressors are rotating in the proper direction. To determine
whether or not compressoi's 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 tlie unit.
3. Reverse any two of the incoming power leads.
4. Turn on power to the unit.
5. Energize each compressor.
The suction and discharge pressure levels should now move
to their nonual start-up levels.
NOTE: When compressors are rotating in the wrong direction,
tlie unit will have increased noise levels and will not provide
heating and cooling.
After a few minutes of reverse operation, the scroll com­
pressor interniJ overload protection will open, which will acti­
vate the unit's lockout and requires a manual reset. Reset is
accomplished by turning the thermostat on and off.
INTERNAL WIRING — Check all electrical connections in
unit control boxes; tighten as required.
CRANKCASE HEATER (SIZE 028 AND UNITS WITH
MOISTUREMISER'M DEHUMIDIFICATION PACKAGE
ONLY) — Crankcase heater(s) is energized as long as there is
power to the unit and the compressor is not operating.
IMPORTANT: Unit power must be on for 24 houm prior to
start-up. Otheiwise, damage to the compressor may result.
EVAPORATOR FAN — Fan belt and vtuiable pulleys are
factoiy-installed. Remove tape from the fan pulley. See
Tables 14-19 for fan performance data. Be sure that fans rotate
in the proper direction. See Table 20 for air quantity limits. See
Tables 21-23 for static pressure information for accessoiles and
options. See Table 24 for fan rpm at motor pulley settings. See
Tables 25 and 26 for evaporator-fan motor data and evaporator­
fan motor efficiency. To alter fan performance, see Evaporator
Fan Performance Adjustment section on page 40.
NOTE: A 3'/2-in. bolt and threaded plate are included in the
installer’s packet for 48TJ020-028 units. They can be added to
tlie motor support channel below the motor mounting plate to
£iid in raising the fan motor.
31