Carrier 38GC - Manual (Page 6)

SINGLE-PHASE compressor motors in 38GC101,
38GC,GF102, 103, 104 units are protected by an
i n t e r n a l current and temperature sensitive
overload.
Single-phase 38GC,GF145, 105 and 38GF106
unit compressors are protected by an internal
thermostat and external current overloads.
THREE-PHASE unit compressors are protected by
an internal thermostat and external current
overloads.
Internal temperature-sensitive overloads reset
automatically when internal motor temperatures
drop to a safe level (overloads may require up to
30 minutes to reset).
When an internal overload is suspected of being
open, check by using an ohmmeter or continuity
tester. See Carrier Standard Service Techniques
Manual, Chapter 2, for complete instructions.
TIME GUARD CIRCUIT (38GC145, 105 and all
38GF units) provides for a 5-minute delay before
restarting compressor after shutdown for any
reason. On starting, the time guard timer causes a
delay of 15 seconds after thermostat closes before
compressor will start. On compressor shutdown,
the timer delays compressor restarting for 4
minutes 45 seconds.
Compressor Removal
1. Shut off power to unit. Vent refrigerant to
atmosphere or use refrigerant removal methods
shown in Carrier Standard Service Techniques
Manual, Chapter 1.
2. Remove top grille and rear access panel.
3. Remove condenser fan motor orifice assembly.
Fan motor wires do not have to be dis­
connected.
4. Remove compressor sound shield (if supplied).
5. Remove power leads from compressor terminal
box, and pressure relief plug from suction line.
Unsweat suction and hot gas lines.
6. Remove compressor hold-down bolts. Lift com­
pressor out thru top of unit.
PUMPDOWN PROCEDURE
The 38GC and GF units may be pumped down
in order to make repairs on low side of system
without losing complete refrigerant charge.
1. Attach pressure gage to suction service valve
gage port.
2. Frontseat the liquid line valve.
3. Jumper low-pressure switch.
4. Start unit and run until suction pressure reaches
5 psig (see Caution).
5. Shut unit off and frontseat suction valve.
6. Vent remaining pressure to atmosphere.
CAUTION- The 38GC and CF conckascr»
Will hold only faciory-supplicd smount of
refrigerant. Additionai refrigerant may eauv
38GF unsts cycle os high prc-ssurcMal
and units to reiie^-c pfes*ure thru
mtemai pressure ix-hef vaive (indicated by a
sudden rii>e of suction pressure t before
satetion pressure reache> 5 psig, if this
oceurs, shut
ut&i off immediately, frontseat
suction vaive and vent renaaining pressure to
A
V
PRESSURE RELIEF PLUG
This plug is a protective device which melts at
210 F relieving excessive system pressure. Remove
plug when soldering on suction tube. For plug
replacement, order Carrier part no. EK02JA203.
REFRIGERANT CHARGING
38GC Units contain correct operating charge for
complete system when connected to Carrier
approved evaporators (capillary tube or thermal
expansion valve controlled) with up to 25 ft of
tubing. When over 25 ft of tubing is used,
additional charge may be required. Use Charging
Chart Method (when available) to check refrigerant
charge or add charge to Carrier approved systems.
To recharge these systems, use Weight Method
when 25 ft or under of interconnecting tubing is
used; Charging Chart Method when over 25 ft of
tubing is used. When charging charts are not
available or when 38GC condensing unit is con­
nected to other than a Carrier evaporator, use
Weight Method of recharging.
Do not connect charging hoses to capillary
controlled systems during initial start procedure. If
necessary, to add manifold gages for servicing, refer
to Carrier Standard Service Techniques Manual,
Chapter 1, pages 1-5, Fig. 8, for bypass method of
returning charge to system.
CAimON: Do mt iheise systems, A
small pverebafj-go may rsistiit m compressor
due fo mfri^ranf flooding,
38GC CHARGING METHODS - When required,
evacuate 38GC systems to 5000 microns (29.7-in.
vacuum) before recharging. Refer to Carrier
Standard Service Techniques Manual, Chapter 1,
for system evacuation-dehydration instructions and
details of charging instructions listed below.
Charging Chart Method
TXV Systems — Use correct charging chart (Fig. 3
thru 8). See Carrier Standard Service Techniques
Manual, Chapter 1, for procedure.
Capillary Tube Systems — Use correct charging
chart (Fig. 9 thru 24). 38GC capillary tube systems
are charged correctly when intersection of system