Carrier 38GC - Manual (Page 7)

suction and discharge pressure lines on charging
chart falls on intersection of indoor air wet bulb
(ewb) and outdoor dry bulb temperature lines.
Weight Method ~ Refer to Table 6 or unit
nameplate for correct system refrigerant charge.
Blow any refrigerant remaining in system before
recharging.
When system is not evacuated, subtract the
following amount from total charge (Table 6).
38GC101,38GC102 - .10 lb (1.6 oz)
38GC103, 104, 145, 105 - .20 lb (3.2 oz)
Keep refrigerant recharge within one oz of
specified charge on 38GC101, 102 systems, and
within 2 oz on 38GC103, 104, 145, 105 systems.
Dial-a-Charge charging cylinder is an accurate
device used to recharge systems by weight. These
cylinders available at refrigeration supply firms.
38GF 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 38GF condensing unit is con­
nected to other than a Carrier evaporator, use
Weight Method of recharging.
A satisfactory operating charge can be obtained
on 38GF thermal expansion valve systems by using
Sight Glass Method. This method may not provide
optimum charge.
38GF CHARGING METHODS - When required,
evacuate 38GF 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 instruction 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). 38GF capillary tube systems
are charged correctly when intersection of system
suction and discharge pressure lines on charging
chart falls on intersection of indoor air wet bulb
(ewb) and outdoor dry bulb temperature lines.
Weight Method — Refer to Table 6 or unit
nameplate for correct system refrigerant charge.
Blow any refrigerant remaining in system before
recharging.
When system is not evacuated, subtract the
following amount from total charge (Table 6).
38GF101, 102 - .10 lb (1.6 oz)
38GF103, 104, 145, 105, 106 - .20 lb (3.2 oz)
Keep refrigerant recharge within one oz of
specified charge on 38GF101, 102 systems and
within 2 oz on 38GF103, 104, 145, 105 and 106
systems.
Dial-a-Charge charging cylinder is an accurate
device used to recharge systems by weight. These
cylinders available at refrigeration supply firms.
Sight Glass Method — A satisfactory operating
charge can be obtained on 38GF TXV systems by
charging to a clear sight glass. For optimum charge,
use Charging Chart Method.
Elevate high-side pressure to 380 ± 10 psig by
blocking condenser fan discharge or condenser
entering air. Service access panel may be adjusted
to bypass entering air. (Do not operate without
panel in place except during charging procedure.)
Charge to a clear sight glass while holding high-side
pressure constant.
38GF106 TXV Systems — Add 11 oz of refrigerant
after clear sight glass is obtained for correct charge.
THERMAL EXPANSION VALVE SYSTEMS
Fig. 3 — 38GC,GF102 Charging Chart