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104 SS-SVX09A-EN
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 refrigerant, without
causing compressor damage. The following discussion describes some of the operational sounds
that differentiate it from those typically associated with a reciprocating compressor. These sounds
do not affect the operation 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 conditions, 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 compressor rattle until the suction pressure climbs and the flow rate increases.
Scroll Compressor Replacement
Table 19 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 refrigerant manifolded system must not be modified in any way.
NOTICE
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 minimum of 18 inches upstream of the oil separator tee. Refer to the illustration
in Figure 53.
Anytime a compressor is replaced, the oil for each compressor within the manifolded set must be
replaced.
The scroll compressor uses Trane OIL-42 without substitution. The appropriate oil charge for a 9 and
10 Ton scroll compressor is 8.5 pints. For a 14 and 15 Ton scroll compressor, 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).
NOTICE
Refrigerant oil is detrimental to some roofing materials. Care must be taken to protect the roof
from oil leaks or spills.