Trane R Series Installation Operation & Maintenance page 108

RTAC-SVX002A-EN
Maintenance Procedures
The evaporator is large enough to hold
all the charge for any unit to below the
centerline of the shell. Therefore, no
special precautions are required to re-
start the unit after isolating the charge in
the evaporator.
Refrigerant Filter Replacement Proce-
dure
A dirty filter is indicated by a temperature
gradient across the filter, corresponding
to a pressure drop. If the temperature
downstream of the filter is 8°F (4.4°C)
lower than the upstream temperature,
the filter should be replaced. A tempera-
ture drop can also indicate that the unit is
undercharged. Ensure proper subcool-
ing before taking temperature readings.
1. With the unit off, verify that the EXV is
closed. Close liquid line isolation valve.
On units with remote evaporators or oil
cooling circuits, close ball valve on oil
cooler liquid line.
2. Attach hose to service port on liquid
line filter flange.
3. Evacuate refrigerant from liquid line
and store.
4. Remove hose.
5. Depress schrader valve to equalize
pressure in liquid line with atmospheric
pressure.
6. Remove bolts that retain filter flange.
7. Remove old filter element.
8. Inspect replacement filter element and
lubricate o-ring with Trane OIL00048.
NOTE: Do not use mineral oil. It will
contaminate the system.
9. Install new filter element in filter hous-
ing.
10. Inspect flange gasket and replace if
damaged.
11. Install flange and torque bolts to 14-
16 lb-ft (19-22 n-m).
12. Attach vacuum hose and evacuate
liquid line.
13. Remove vacuum hose from liquid
line and attach charging hose.
14. Replace stored charge in liquid line.
15. Remove charging hose.
16. Open liquid line isolation valve. On
units with remote evaporators or oil cool-
er circuits, open oil cooler liquid line ball
valve.
Lubrication System
The lubrication system has been de-
signed to keep most of the oil lines filled
with oil as long as there is a proper oil
level in the oil sump.
The total oil charge can be removed by
draining the oil system, oil return line
from the evaporator, the evaporator, and
the compressor. Very small quantities of
oil may be found in other components.
Like many machines, an excessive oil
charge can cause operational problems.
Special care should always be taken to
avoid adding extra oil.
Units that exhibit the symptoms of an oil
overcharge at high loads may still run
fine at light loads. An oil overcharged
unit may result in an evaporator limit
warning or even a low liquid level or low
evap temp (LRTC) diagnostic. An oil
overcharged unit may exhibit increased
approach temperatures and decreased
overall unit efficiency.
Oil Charging Procedure
Proper charging of the oil system is criti-
cal to the reliability of the compressor
and chiller. Too little oil can cause the
compressor to run hot and inefficient.
When taken to an extreme, low oil level
may result in instant failure of the com-
pressor. Too much oil
will result in high oil circulation rates
which will foul the condenser and evapo-
rator performance. This will result in inef-
ficient operation of the chiller. Taken to
an extreme, high oil levels may result in
erratic expansion valve control or shut
down of the chiller due to low evaporator
refrigerant temperature.
Too much oil may contribute to long term
bearing wear. Additionally, excessive
compressor wear is probable when the
compressor is started with the oil lines
dry.
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