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3. Leak test, evacuate, and dehydrate the system.
4. Charge the system. When initially charging the high side
of the system with liquid refrigerant, all service valves
should be closed (front seated). This will prevent
refrigerant from migrating to the compressor crankcase
and into the oil, causing a flooded start.
The system is now charged and ready for start-up.
Recheck the oil levels and add or remove oil as neces-
sary. Open (backseat) the discharge service valve and
any oil equalization lines on parallel systems. Open the
suction service valve 1/2 to 1 turn, or enough to allow
the compressor to run without tripping the low-pressure
switch in order to prevent damage to the compressor
from any liquid refrigerant floodback.
5. On water-cooled condensing systems, open water supply
valve and allow water to reach condenser. On air-cooled
condensing systems, turn condenser fan on when the
compressor unit is started.
6. Ensure that all evaporator connections are opened and
fans started.
7. On systems with more than one compressor in parallel,
start one compressor at a time.
COMPRESSOR START-UP
1. After circuit breaker and control circuit switches are
placed in the ON position and the compressor starts, lis-
ten for unusual sounds. If unusual sounds are heard, shut
down the compressor, investigate the cause, and correct.
Possible problems are:
• Excessive vibration
• Excessive oil
• Liquid slugging
• Low oil
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