AGL_HP_VS_YHV_RG_RT_EN_Rev00 35
To disconnect:
Using a pipe cutting tool, cut off the suction and discharge
lines in such a manner that the new compressor can easily be
re-connected into the system.
Heat joint areas 2 and 3 slowly and uniformly until the braze
material sof tens and the tube end can be pulled out of the
fitting.
To reconnect:
Recommended brazing material: Silfos with minimum 5 % silver or silver braze used on other
compressors.
Due to the different thermal properties of steel and copper, brazing procedures may have to be
changed from those commonly used.
NOTE: Since the discharge stub contains a check valve, care must be taken not to overheat
it to prevent brazing material from flowing into it.
6.5 Replacing a compressor
CAUTION
Inadequate lubrication! Bearing destruction! For systems with a
accumulator, exchange the accumulat
or after replacing a compressor with a
burned-
out motor. The accumulator oil return orifice or screen may be plugged
with debris or may become plugged. This will result in starvation of oil to the
new compressor and a second failure.
oil completely from the replaced compressor.
6.5.1 Compressor replacement
In the case of A2L- or A3-refrigerant compressor replacement, the oil has to be drained out of the
compressor and the compressor should be flushed with dry nitrogen. DO NOT close the stubs with
plugs.
In the case of a motor burnout, the majority of contaminated oil will be removed with the compressor.
The rest of the oil is cleaned through the use of suction and liquid line filter dryers. A 100 % activated
alumina suction line filter dryer is recommended but must be removed after 72 hours.
It is highly recommended that the suction accumulator be replaced if the system contains
one. This is because the accumulator oil return orifice or screen may be plugged with debris or may
become plugged shortly after a compressor failure. This will result in starvation of oil to the
replacement compressor and a second failure. When a compressor is exchanged in the field, it is
possible that a major portion of the oil may still be in the system. While this may not affect the
reliability of the replacement compressor, the extra oil will add to rotor drag and increase power
usage.
6.5.2 Start-up of a new or replacement compressor
Rapid charging only on the suction side of a scroll-equipped system can occasionally result in a
temporary no-start condition for the compressor. The reason for this is that, if the flanks of the scrolls
happen to be in a sealed position, rapid pressurisation of the low side without opposing high-side
pressure can cause the scrolls to seal axially. As a result, until the pressures eventually equalise,
the scrolls can be held tightly together preventing rotation. The best way to avoid this situation is to
charge on both the high and low sides simultaneously at a rate which does not result in axial loading
of the scrolls.
A minimum suction pressure specified in the published operating envelope must be maintained
during charging. Allowing the suction pressure to drop below that value may overheat the scrolls and
cause early drive bearing and moving parts damage. Never install a system in the field and leave it
unattended when it has no charge, a holding charge, or with the service valves closed without
securely electrically locking out the system. This will prevent unauthorised pers onnel from
accidentally operating the system and potentially ruining the compressor by operating with no
ref rigerant. Do not start the compressor while the system is in a deep vacuum. Internal arcing
may occur when a scroll compressor is started in a vacuum causing burnout of the internal lead
connections.
Figure 25: Tube connecting areas
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