Amana VXC20 Series, Installation & Service Reference

Page: 49 / 60

49
Adjust Refrigerant level
Using service equipment, add or recover refrigerant
according to the calculation in Step 1. Allow system to
stabilize for 10 minutes after adjusting charge level.
Measure Subcooling to Verify Proper Charge
NOTE: Charging equipment must use dedicated PVE
oil gauges and hoses.
1. Purge gauge lines.
2. Connect service gauge manifold to base valve service
ports.
3. Convert the liquid pressure to temperature using a
temperature/pressure chart.
4. Temporarily install a thermometer on the liquid line at
the liquid line service valve.
a. Ensure the thermometer makes adequate contact
and is insulated for best possible readings.
5. Subtract the liquid line temperature from the converted
liquid pressure to determine subcooling.
6. Before starting the Subcooling adjustment, make sure
the outdoor ambient temperature is in a below range
and the unit is operating at 100% capacity.
7. For EEV Indoor Unit: If the system subcooling is not
within the ranges shown in the following table, adjust
subcooling according to the following procedure:
a. If subcooling is low, add charge to adjust the
subcooling as specified in the following table.
b. If subcooling is high, remove chargee to lower the
subcooling to 8° ± 1°F (*1).
SUBCOOLING = (SAT. LIQUID TEMP.) - (LIQUID LINE TEMP.)
SUPERHEAT = (SUCT. LINE TEMP.) - (SAT. SUCT. TEMP.)
Charging Table
OD Ambient Temp
(degF)
< 65°F 65°F to 105°F > 105°F
Subcooling
(degF)
Weigh in
Charge
8°F ± 1°F
Weigh in
Charge
NOTE: Subcooling information is valid only while the unit is
operating at 100% capacity or 100% of compressor speed in
CHARGE MODE. Compressor speed is displayed under STATUS
menu in the thermostat.
8. For TXV Indoor Unit
The system subcooling should be 8°F ± 1°F. If not in
that range, adjust subcooling and superheat according
to the following procedure.
a. If subcooling and superheat are low, adjust TXV to
8°F ± 1°F superheat, then check subcooling.
NOTE: To adjust superheat, turn the valve stem
clockwise to increase and counter clockwise to
decrease.
b. If subcooling is low and superheat is 8°F ± 1°F,
add charge to rise subcooling to 8°F ± 1°F, then
check superheat.
c. If subcooling is low and superheat is high, add
charge to rise subcooling to 8°F ± 1°F, then check
superheat.
d. If subcooling is 8°F ± 1°F and superheat is high,
adjust the TXV valve to 8°F ± 1°F superheat, then
check subcooling.
e. If subcooling and superheat are high, adjust the
TXV valve to 8°F ± 1°F superheat, then check
subcooling.
f. If subcooling is high and superheat is 8°F ± 1°F,
remove charge to lower the subcooling to 8°F ±
1°F, then check superheat.
g. If subcooling is high and superheat is low, adjust
the TXV valve to 8°F ± 1°F superheat and remove
charge to low the subcooling to 8°F ± 1°F.
h. If subcooling is 8°F ± 1°F and superheat is low,
adjust the TXV valve to 8°F ± 1°F superheat and
remove charge to lower the subcooling 8°F ± 1°F,
then check the superheat.
NOTE: Not more than 0.5 lb. (8 Oz.) of refrigerant
must be added to the system in order to achieve
the target subcooling. It is recommended to add
4 oz. refrigerant each time and try adjusting the
TXV and let the system stabilize.
C
HECK THE
S
CHRADER PORTS FOR LEAKS AND TIGHTEN VALVE CORES
,
IF
NECESSARY
. I
NSTALL CAPS FINGER
-
TIGHT
.
NOTICE
D
O
NOT
ADJUST THE CHARGE BASED ON SUCTION PRESSURE UNLESS
THERE IS A GROSS UNDERCHARGE
.
NOTICE