AAON LL-540 - Manual (Page 20)

20
Outdoor Mechanical Room
Failure to observe the following instructions
will result in premature failure of your
system, and possible voiding of the
warranty.
Never turn off the main power supply to the
unit, except for complete shutdown. When
power is cut off from the unit, any
compressors using crankcase heaters cannot
prevent refrigerant migration. This means
the compressor will cool down, and liquid
refrigerant
may accumulate in the
compressor. The compressor is designed to
pump refrigerant gas and damage may occur
when power is restored if liquid enters the
compressor.
Before unit operation, the main power
switch must be turned on for at least 24
hours for units with compressor crankcase
heaters. This will give the crankcase heater
time to clear any liquid accumulation out of
the compressor before it is required to run.
Never cut off the main power supply to the
unit, except for complete shutdown. Always
control the system from the building
management system, or control panel, never
at the main power supply (except for
emergency or for complete shutdown of the
system).
Rotation must be checked on all
MOTORS AND COMPRESSORS of
three phase units. All motors, to
include and not be limited to pump
motors and condenser fan motors,
should all be checked by a qualified
service technician at startup and any
wiring alteration should only be made
at the unit power connection.
CAUTION
Scroll compressors are directional
and will be damaged by operation in
the wrong direction. Low pressure
switches on compressors have been
disconnected after factory testing.
Rotation should be checked by a
qualified service technician at startup
using suction and discharge pressure
gauges and any wiring alteration
should only be made at the unit
power connection.
CAUTION
CRANKCASE HEATER
OPERATION
Units may be equipped with
compressor crankcase heaters,
which should be energized at least
24 hours prior to cooling operation, to
clear any liquid refrigerant from the
compressors.
CAUTION
COMPRESSOR CYCLING
5 MINUTE MINIMUM OFF TIME
To prevent motor overheating
compressors must cycle off for a
minimum of 5 minutes.
5 MINUTE MINIMUM ON TIME
To maintain the proper oil level
compressors must cycle on for a
minimum of 5 minutes.
The cycle rate must not exceed 6
starts per hour.
WARNING