Trane R Series Installation Operation & Maintenance page 106

RTAC-SVX002A-EN
Maintenance Procedures
4. Begin semi-automatic vacuum proce-
dure.
5. When vacuum is complete (indi-
cated), manually isolate the unit from
vacuum.
6. Charge unit through the filter housing
port per Tables.
7. When charging is complete, shut
evaporator service valve and disconnect
vacuum and charging hoses.
Field Refrigerant Charging Procedure
Follow this procedure when the unit
is empty of all refrigerant and under a
vacuum.
Add the charge through the evaporator
service valve.
CAUTION
Evaporator Damage!
Water must be flowing through the
evaporator during the entire charging
process to avoid freezing and ruptur-
ing of the evaporator tubes. Charge
first with vapor to avoid freezing
tubes.
1. Note the weight of the amount of
charge removed. Compare it to Table
- Table A difference in charge may indi-
cate a leak.
2. Attach charging hose to evaporator
service valve (3/8" (9mm) flare). Open
service valve.
3. Add charge to evaporator to bring total
circuit charge up to the level indicated in
the above chart.
4. Close service valve and disconnect
charging hose.
Adding charge:
This procedure should be followed when
adding charge to an undercharged unit.
When low charge is indicated by low
subcooling in the liquid line, charge
should be added until sufficient subcool-
ing is achieved.
1. Attach charging hose to evaporator
service valve (3/8" (9mm) flare). Open
service valve.
2. Add 10 pounds of refrigerant (R-134a)
charge.
3. Close valve, remove charging hose
and start unit. Monitor subcooling.
4. If subcooling is still insufficient, return
to step #1.
NOTE: Proper subcooling can be deter-
mined from run log history, service expe-
rience, or by contacting Trane technical
service.
Charge Isolation in the high or low
side of system
All the refrigerant may be trapped into
the high side (condenser) of the unit for
maintenance on the compressor or low
side. With the suction line service valve
option, charge may also be isolated in
the evaporator for maintenance on the
compressor or the high side. It is prefer-
able to isolate the charge in the evapora-
tor, if this option is available.
High side charge isolation procedure:
1. Make sure circuit is off.
2. Shut liquid line service valve.
3. Shut oil return line service valve.
4. Start circuit with the service tool in
charge isolation mode:
– All fans will turn on
– EXV will open 100%
– Oil return line solenoid (if included) will
open
– Unit will start at minimum load
– Unit will run until it cuts out on low
pressure (~6 psia) (0.41 bar)
– Monitor pressure with a suction gauge
5. When unit trips, the discharge check
valve will close.
6. Close discharge isolation valve.
7. Close oil line shut off valve.
8. Remove the remainder of the charge
with transfer pump.
NOTE: Recommendation: Do not pump
remaining charge into high side. This
may introduce non condensable gasses
and other contaminants into the unit.
9. The low side and compressor may be
serviced at this time.
106