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Service & Maintenance
Compressor Operational Sounds
Because of the scroll compressor design, it emits a higher
frequency tone (sound) than a reciprocating compressor. It
is designed to accommodate liquids, both oil and refriger-
ant, without causing compressor damage. The following dis-
cussion describes some of the operational sounds that dif-
ferentiate it from those typically associated with a recipro-
cating compressor. These sounds do not affect the opera-
tion or reliability of the compressor.
At Shutdown:
When a Scroll compressor shuts down, the gas within the
scroll expands and causes momentary reverse rotation until
the discharge check valve closes. This results in a “flutter”
type sound.
At Low Ambient Start-Up
When the compressor starts up under low ambient condi-
tions, the initial flow rate of the compressor is low due to the
low condensing pressure. This causes a low differential
across the thermal expansion valve that limits its capacity.
Under these conditions, it is not unusual to hear the com-
pressor rattle until the suction pressure climbs and the flow
rate increases.
Scroll Compressor Replacement
Table 6-1 lists the specific compressor electrical data and
the circuit breaker operating ranges.
The compressor manifold system was purposely designed
to provide proper oil return to each compressors. The refrig-
erant manifolded system must not be modified in any way.
Note: Altering the manifold piping may cause oil
return problems and compressor failure.
Should a compressor replacement become necessary and
a suction line filter drier is to be installed, install it a mini-
mum of 18 inches upstream of the oil separator tee. Refer
to the illustration in Figure 6-1.
Anytime a compressor is replaced, the oil for each com-
pressor within the manifolded set must be replaced.
The scroll compressor uses Trane OIL-42 without substi-
tution. The appropriate oil charge for a 9 and 10 Ton scroll
compressor is 8.5 pints. For a 14 and 15 Ton scroll com-
pressor, use 13.8 pints.
Note: Do Not release refrigerant to the
atmosphere! If adding or removing refrigerant is
required, the service technician must comply with
all Federal, State and local laws. Refer to general
service bulletin MSCU-SB-1 (latest edition).
Note: Refrigerant oil is detrimental to some roofing
materials. Care must be taken to protect the roof
from oil leaks or spills.
Table 6-1
Compressor Circuit Breaker Data
Voltage Comp RLA LRA Must Must
Tons Hold Trip
200 9 41.4 269.0 50.4 58.0
230 9 41.4 251.0 50.4 58.0
460 9 18.1 117.0 22.0 25.3
575 9 14.4 94.0 17.5 20.2
380/415 9 17.2 110.0 20.9 24.1
200 14 60.5 404.0 73.7 84.7
230 14 60.5 376.0 73.7 84.7
460 14 26.3 178.0 32.0 36.8
575 14 21.0 143.0 25.6 29.4
380/415 14 26.2 174.0 31.9 36.7
Figure 6-1
Suction Line Filter/Drier Installation
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