Carrier 38ED - Manual (Page 7)

Table 5 — Refrigerant Charging Methods
MODEL
METHODS OF CHECKING OR
ADJUSTING CHARGE
METHODS FOR COMPLETE
RECHARGING
38ED System Refrigerant Control System Refrigerant Control
Non TXV TXV Non TXV TXV
ALL
Chargemaster®
or
Charging Chart
Sight
Glass*
Weight Method
plus
Chargemaster or
Charging Chart
Weight Method
plus
Sight Glass*
'Sight glass field supplied and installed in liquid refrigerant line
Table 6 — Service Data
MODEL
38ED
R-22 CHARGE*
(lb)
CONDENSER
FAN RPM
018 6 5
024 74
830
030 7 6
036 8 5
042 90
048 8.0 840
060 10 2
'Factory refrigerant charge is adequate when evaporator and con­
densing unit are the same size and are connected with 25 ft or
less of field-supplied tubing of recommended size or Carrier
accessory tubing
(AccuRater™ System)
2. Measure suction pressure by attaching a gage to
suction valve service port.
3. Measure suction line temperature by attaching a
service thermometer to unit suction line near suc­
tion valve. (Insulate thermometer for accurate
readings.)
4. Measure outdoor (condenser inlet) air dry-bulb
temperature with a second thermometer.
5. Refer to Charging Chart (Fig. 7). Find air tem­
perature entering condenser and project hori­
zontally to curve showing suction pressures
(psig at suction valve).
6. From this intersection, project vertically down­
ward to suction line temperature.
7. If unit has a higher suction line temperature than
charted temperature, add refrigerant until
charted temperature is reached.
8. If unit has a lower suction line temperature than
charted temperature, bleed refrigerant until
charted temperature is reached.
9. If air temperature entering condenser or pressure
at suction valve changes, charge to new suction
line temperature indicated on chart.
CHARGEMASTER® METHOD — Operate unit
for 10 minutes before using Chargemaster (Carrier
Part No. 38GC680004).
1. Tape Chargemaster feeler bulb to suction line
close to condensing unit. Insulate bulb. Ensure
suction line is clean for good contact with bulb.
(Uninsulated bulb or dirty suction line will seri­
ously affect accuracy of temperature readings.)
2. Connect refrigerant drum to Chargemaster inlet
port keeping drum in position for vapor charging.
3. Connect Chargemaster outlet port to unit suction
valve service port.
4. Crack valves on refrigerant drum and Charge-
master to purge lines from drum to suction valve.
After purging lines, close valve on Chargemaster
only.
5. Measure outdoor air dry-bulb temperature.
6. Crack unit suction valve and read evaporator
temperature at red needle position on Charge-
master temperature gage and suction line tem­
perature at black needle position.
7. Enter Chargemaster Charging Chart, Table 7, at
outdoor air temperature (step 5) and evaporator
temperature (step 6). Find the suction line tem­
perature required for correct system charge. If