Noisy Compressor - Bryant Base Series Application Manual And Service Manual

Residential Air Conditioners and Heat Pumps Using R-22 and Puron® Refrigerant: Application Guideline and Service Manual

Noisy Compressor

Noise may be caused by a variety of internal and external factors.
Careful attention to the "type" of noise may help identify the source.
The following are some examples of abnormal conditions that may
create objectionable noise:
1. A gurgling sound may indicate a liquid refrigerant floodback during
operation. This could be confirmed if there is no compressor
superheat. A compressor superheat of "0" degrees would indicate
liquid refrigerant returning to the compressor.
reasons for floodback are: loss of evaporator blower, dirty coils, and
improper airflow.
2. A rattling noise may indicate loose hardware. Inspect all unit
hardware including the compressor grommets.
3. A straining (hard start) or vibration occurring at start up but clears
quickly after could indicate an off cycle refrigerant migration issue.
Refrigerant migration can occur when a compressor is off and
refrigerant vapor transfers from other areas of the system, settles
into the compressor as it is attracted to the oil, and then condenses
into the oil. Upon start up, the compressor draws suction from
within itself first and lowers the boiling point of the refrigerant that
is entrained in the oil. This can cause the liquid refrigerant and oil
to boil into the compression area or liquid refrigerant to wipe off oil
films that are critical for proper lubrication. Migration is worsened
by greater temperature differentials and/or extra refrigerant in the
system. Prevention of migration can be reduced by various options
but some of the more common remedies is to verify proper charge
and add a crankcase heater where this situation is suspected.
4. Operational vibration could indicate a charge issue. Verify charge
and ensure proper piping and structural penetration insulation.
Tubing that is too rigid to building rafters without proper insulation
could transfer noise throughout the structure. On some occasions a
sound dampener or mass weight (RC part no. 328209-751) placed
on the vibrating tubing has been known to reduce this noise.
Utilizing compressor split post grommets (see
reduce this vibration if piping cannot be remedied.
5. An operational high pitch frequency or "waa waa" sound that
appears to resonate through the suction line could indicate a need to
add more flex or muffling in the lines. This has been occasional in
scroll compressor applications and is usually remedied by adding a
field-fabricated suction line loop (see
compressors may have a noticeable discharge pulsation that could
be remedied with a field installed discharge muffler.
loop by continuous tubing with no more than 12 inches vertical and
6 inch horizontal loop.
6. An internal "thunking", "thumping", "grinding" or "rattling" noise
could indicate compressor internal failures and may be verified by
comparing the compressor amperage to what the compressor should
be drawing according to a manufacturer's performance data.
7. A whistling or squealing noise during operation may indicate a
partial blockage of the refrigerant charge.
8. A whistle on shut down could indicate a partial leak path as
refrigerant is equalizing from high to low side. On occasion, an
in-line discharge check valve has prevented this sound.
9. If a compressor hums but won't start it could indicate either a
voltage or amperage issue. Verify adequate voltage and operational
start components if installed. If it is drawing excessive amperage
and voltage doesn't appear to be the problem it may be assumed a
locked condition. Ensure refrigerant has had ample time to
equalize and boil out of the compressor before condemning.
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Most common
Fig. 16) may also
Fig. 17). Reciprocating
Recommend
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10. When a heat pump switches into and out of defrost, a "swooshing"
noise is expected due to the rapid pressure change within the
system. However customers sometimes complain that the noise is
excessive, or it is sometimes accompanied by a "groaning, or
howling" noise. When receiving these complaints, Quiet Shift-2 (if
available) may improve the noise, but will probably not eliminate it
totally. Check that the defrost thermostat or thermistor is operating
properly. Insulating the defrost sensing device may also help. If the
howling or groaning noise is intermittent, replacing the reversing
valve may or may not help.
11. Rattling that occurs during a shift into or out of defrost on a heat
pump could indicate a pressure differential issue. This is usually a
brief occurrence (under 60 seconds) and can be remedied by
incorporating Quiet Shift-2, if available. This is a device that shuts
down the compressor during the defrost shift for approximately 1
minute allowing the pressures to equalize. It is enabled by either a
dip switch setting on the defrost board, or in the User Interface on
communicating systems. Verify proper system charge as well.
Fig. 16 – Split Post Grommet part number: KA75UG100
Fig. 17 – Suction Line Loop
A07124
A07123