SERVICING
32
105°F. If ambient temperature is out of range, don’t adjust
subcooling.
2. For best results, temporarily install a thermometer on the
liquid line at the liquid line service valve and 4-6" from the
compressor on the suction line. Ensure the thermometer
makes adequate contact and is insulated for best possible
readings. Use liquid line temperature to determine sub-
cooling and vapor temperature to determine superheat.
NOTE: AN OPTIONAL METHOD IS TO LOCATE THE THERMOMETER
AT
THE SUCTION LINE SERVICE VALVE. ENSURE THE THERMOMETER
MAKES
ADEQUATE CONTACT AND IS INSULATED FOR BEST POSSIBLE
READINGS
.
3. The system subcooling should be 8°F ± 1°F(*1). If not in that
range, adjust subcooling and superheat according to the
following procedure.
a. If subcooling and superheat are low, adjust TXV to 7 to
9°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 7 to 9°F, add charge
to rise subcooling to 8°F ± 1°F(*1), then check superheat.
c.If subcooling is low and superheat is high, add charge to
rise subcooling to 8°F ± 1°F(*1), then check superheat.
d. If subcooling is 8°F ± 1°F(*1) and superheat is high, adjust
the TXV valve to 7 to 9°F superheat, then check subcooling.
e. If subcooling and superheat are high, adjust the TXV valve
to 7 to 9°F superheat, then check subcooling.
f. If subcooling is high and superheat is 7 to 9°F, remove
charge to lower the subcooling to 8°F ± 1°F(*1), then check
superheat.
g. If subcooling is high and superheat is low, adjust the TXV
valve to 7 to 9°F superheat and remove charge to low the
subcooling to 8°F ± 1°F(*1).
h. If subcooling is 8°F ± 1°F(*1) and superheat is low, adjust
the TXV valve to 7 to 9°F superheat and remove charge to
lower the subcooling 8°F ± 1°F(*1), then check the
superheat.
*1.10°F ± 1°F only for DZ20VC0601
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.
4. Disconnect manifold set. Installation is complete.
SUBCOOLING ADJUSTMENT ON EEV APPLICATIONS
NOTE: Subcooling information is valid only while the unit is
operating at 100% capacity or 100% compressor speed in
CHARGE MODE.
Compressor speed is displayed under STATUS menu in the
thermostat.
1. Run system at least 20 minutes to allow pressure to
stabilize. During the adjustment of subcooling, ambient
temperature should be greater than 65°F and less than
105°F. If ambient temperature is out of range, don’t adjust
subcooling.
2. For best results, temporarily install a thermometer on the
liquid line at the liquid line service valve. Ensure the
thermometer makes adequate contact and is insulated for
best possible readings. Use liquid line temperature to
determine sub-cooling.
3. The system subcooling should fall in the range shown in
following table. If not in that range, adjust subcooling
according to the following procedure.
a. If subcooling is low, add charge to adjust the
subcooling to 8°F ± 1°F(*1).
b. If subcooling is high, remove charge to lower the
subcooling to specified range.
*1.10°F ± 1°F only for DZ20VC0601
NOTE: Not more than 0.8 lb. (13 oz.) of refrigerant be added
to the system at a time to achieve the target
subcooling. It is recommended adding 4 oz.
refrigerant each time, then wait 20 minutes to
stabilize the system.
4. Disconnect manifold set. Installation is complete.
S-110 CHECKING THERMOSTATIC EXPANSION VALVE
OPERATION
1. Remove the remote bulb of the thermostatic expansion valve
from the suction line.
2. Start the system and cool the bulb in a container of ice
water, closing the valve. As you cool the bulb, the suction
pressure should fall and the suction temperature will rise.
3. Next warm the bulb in your hand. As you warm the bulb,
the suction pressure should rise and the suction
temperature will fall.
4. If a temperature or pressure change is noticed, the
expansion valve is operating. If no change is noticed, the
valve is restricted, the power element is faulty, or the
equalizer tube is plugged.
5. Capture the charge, replace the valve and drier, evacuate
and recharge.
S-114 NON-CONDENSABLES
If non-condensables are suspected, shut down the system and
allow the pressures to equalize. Wait at least 15 minutes. Com-
pare the pressure to the temperature of the coldest coil since this
is where most of the refrigerant will be. If the pressure indicates
a higher temperature than that of the coil temperature, non-
condensables are present.
Non-condensables are removed from the system by first removing
the refrigerant charge, replacing and/or installing liquid line drier,
evacuating and recharging.
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