Charging - Daikin ComfortNet DX7TC Service Instructions Manual

SERVICING
S-103 CHARGING
REFRIGERANT UNDER PRESSURE!
• Do not overcharge system with refrigerant.
• Do not operate unit in a vacuum or at negative pressure.
Failure to follow proper procedures may cause property damage,
personal injury or death.
Use refrigerant certified to AHRI standards. Used refrigerant may
cause compressor damage and is not covered under the warranty.
Most portable machines cannot clean used refrigerant to meet AHRI
standards.
Damage to the unit caused by operating the compressor with the
suction valve closed is not covered under the warranty and may
cause serious compressor damage.
Charge the system with the exact amount of refrigerant. Refer
to the specification section or check the unit nameplates for the
correct refrigerant charge. An inaccurately charged system will
cause future problems.
NOTE: R410A should be drawn out of the storage container
or drum in liquid form due to its fractionation properties, but
should be "Flashed" to its gas state before entering the system.
There is commercially available restriction devices that fit into
the system charging hose set to accomplish this. DO NOT charge
liquid R410A into the compressor.
NOTE: Power must be supplied to the 18 SEER outdoor units
containing ECM motors before the power is applied to the indoor
unit. Sending a low voltage signal without high voltage power
present at the outdoor unit can cause malfunction of the control
module on the ECM motor.
Adequate refrigerant charge for the matching evaporator
coil or air handler and 15 feet of line set is supplied with the
condensing unit. If using evaporator coils or air handlers other
than HSVTC coil it may be necessary to add or remove refrigerant
to attain proper charge. If line set exceeds 15 feet in length,
refrigerant should be added at .6 ounces per foot of liquid line.
NOTE: The outdoor temperature should be 60°F or higher
when charging the unit. Charge should always be checked using
subcooling when using TXV equipped indoor coil to verify proper
charge. Open the suction service valve first! If the liquid service
valve is opened first, oil from the compressor may be drawn
into the indoor coil TXV, restricting refrigerant flow and affecting
operation of the system.
WARNING
CAUTION
CAUTION
When opening valves with retainers, open each valve only
until the top of the stem is 1/8" from the retainer. To avoid loss
of refrigerant, DO NOT apply pressure to the retainer. When
opening valves without a retainer remove service valve cap and
insert a hex wrench into the valve stem and back out the stem by
turning the hex wrench counterclockwise. Open the valve until it
contacts the rolled lip of the valve body.
NOTE: These are not back-seating valves. It is not necessary to
force the stem tightly against the rolled lip.
After the refrigerant charge has bled into the system, open the
liquid service valve. The service valve cap is the secondary seal
for the valve and must be properly tightened to prevent leaks.
Make sure cap is clean and apply refrigerant oil to threads and
sealing surface on inside of cap. Tighten cap finger-tight and then
tighten additional 1/6 of a turn (1 wrench flat) to properly seat
the sealing surfaces.
EXPANSION VALVE SYSTEM
NOTE: Units matched with indoor coils equipped with non-
adjustable TXV should be charged by subcooling only.
NOTE: The TXV should NOT be adjusted at light load conditions
55º to 60ºF. Use the following guidelines and methods to check
unit operation and ensure that the refrigerant charge is within
limits. Charge the unit on low stage.
Units Equipped with Adjustable Expansion Valves should
be charged by Subcooling and Superheat adjusted only if
necessary.
1. Purge gauge lines. Connect service gauge manifold to
base-valve service ports. Run the system in low stage at
least 10 minutes to allow pressure to stabilize.
2. 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 subcooling and
vapor temperature to determine superheat.
3. Check subcooling and superheat. Systems with TXV application
should have a subcooling of 5 to 7°F and superheat of 7 to 9°F.
A. If subcooling and superheat are low, adjust TXV to 7
to 9ºF superheat, and 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 high, add charge
to raise subcooling to 5 to 7 °F then check superheat.
C. If subcooling and superheat are high, adjust TXV valve
to 7 to 9 ºF superheat, then check subcooling.
D. If subcooling is high and superheat is low, adjust TXV
valve to 7 to 9 ºF superheat and remove charge to
lower the subcooling to 5 to 7 ºF.
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