Carrier 38QB - Manual (Page 5)

REPLACE THE ACCURATER™ REFRIGER­
ANT CONTROL PISTON IN THE INDOOR
COIL AS REQUIRED before connecting refriger­
ant lines. See Table I. Correct piston is supplied
with 38QB unit. For piston replacement instruc­
tions, see AccuRater Servicing on page 15.
CONNECT REFRIGERANT LINES to fittings on
unit suction and liquid service valves (Fig. 1).
Liquid service valve has flare fitting; suction service
valve has Compatible Fitting. Make suction line
connection first. Slide flare nut on liquid line, then
flare and connect liquid line. Use a maximum
torque of 15ft-lb (20N-m) to tighten flare nut. (Do
not disassemble AccuRater.) Unit Compatible
Fitting permits mechanical or sweat connection as
described below.
When a 7/8-in. (22.22-mm) field-supplied suction
line is used on 38QB036,042,048 and 060, a field-
supplied 3/4-in. (19.05-mm) to 7/8-in. (22.22-mm)
suction line adapter must be provided (not required
if 38LS accessory tubing is used).
When a 1-1/8in. (28.57-mm) field-supplied
suction line is used on 38QB042,048 and 060, use
accessory adapter 28AU900061 or other field-
supplied connection. Sweat connect refrigerant
suction line to 1-1/8 in. (28.57-mm) end of adapter.
Connect 3/4-in. (19.05-mm) end of adapter to unit
suction line Compatible Fitting.
Mechanical Connection to Compatible Fitting
(Mate one set of connections at a time.)
1. Loosen nut on Compatible Fitting one turn. Do
not remove.
2. Remove plug and be sure O-ring is in the groove
inside the Compatible Fitting.
3. Cut tubing to correct length.
4. Insert tube into Compatible Fitting until it
bottoms.
5. Tighten nut until it bottoms on back coupler
flange. Keep tube bottomed in Compatible
Fitting while tightening nut.
Sweat Connection to Compatible Fitting (Use
refrigerant grade tubing.)
1. Remove locking nut, rubber O-ring and Schrader
core from valve.
2. Cut tubing to correct length.
3. Insert tube into Compatible Fitting. Wrap top
and bottom of service valves in wet cloth to pre­
vent damage by heat. Solder with low tempera­
ture (430 F [221 C]) silver alloy solder.
4. Replace Schrader core.
5. Evacuate or purge system with field-supplied
refrigerant.
Step 4 — Make Electrical Connections — Field
wiring must comply with local and national fire,
safety and electrical codes. Voltage to unit must be
within permissible limits of voltages indicated on
nameplate. Contact local power company for cor­
rection of improper line voltage.
Do not apply units in system where voltage may
fluctuate above or below permissible limits.
When making electrical connections, provide
clearance at unit for refrigerant piping connections.
See Table 4 for recommended wire and fuse sizes.
INSTALL A BRANCH CIRCUIT DISCONNECT
PER NEC of adequate size to handle unit starting
current. Provide a separate disconnect for outdoor
unit, indoor unit and for each accessory electric
heater circuit as required. (See Indoor Unit and
Electric Heater Installation, Start-Up and Service
Instructions.) Locate disconnect(s) within sight
from and readily accessible from the unit per section
440-14 of National Electrical Code (NEC).
ROUTE LINE POWER LEADS INTO UNIT —
Extend leads from disconnect thru power wiring
hole provided (see Fig. 1) and into unit splice area.
Remove top cover to gain access to unit wiring.
CONNECT GROUND LEAD AND POWER
WIRING — Connect ground lead to a ground lug
in control box for safety. Then connect power
wiring. See Fig. 4. Splice line power leads to yellow
and black pigtails. Use wire nuts and tape at each
connection. Connect unit wiring to copper power
wiring.
Fig. 4 — Line Power Connections
SEE INDOOR UNIT AND ELECTRIC HEATER
INSTALLATION, START-UP AND SERVICE
INSTRUCTIONS for line power wiring details. All
control wiring is shown in this booklet.