SERVICING
94
WARNING
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.
CAUTION
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 sys-
tem 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 compres-
sor may be drawn into the indoor coil TXV, restricting
refrigerant flow and affecting operation of the system.
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 refriger-
ant 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 con-
tact 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 super-
heat of 7 to 9 °F.
a. If subcooling and superheat are low, adjust TXV to 7 to
9 ºF 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.
