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IMPORTANT INSTALLER NOTE
For improved start-up performance, wash the indoor
coil with a dishwasher detergent.
CRANKCASE HEATERS
All units covered in this manual are provided with
compressor crankcase heat.
This crankcase heater is a band type heater located
around the bottom of the compressor. This heater is
controlled by the crankcase heater relay. The heater is
only energized when the compressor is not running.
Crankcase heat is essential to prevent liquid refrigerant
from migrating to the compressor, preventing oil pump
out on compressor start-up and possible bearing or
scroll vane failure due to compressing a liquid.
The decal in Figure 7 is affixed to all model units
detailing start-up procedure. This is very important.
Please read carefully.
FIGURE 7
START-UP LABEL
IMPORTANT
These procedures must be followed at
initial start-up and at any time power has
been removed for 12 hours or longer.
To prevent compressor damage which
may result from the presence of liquid
refrigerant in the compressor crankcase.
1. Make certain the room thermostat is in
the "off" position (the compressor is
not to operate).
2. Apply power by closing the system
disconnect switch. This energizes the
compressor heater which evaporates
the liquid refrigerant in the crankcase.
3. Allow 4 hours or 60 minutes per pound
of refrigerant in the system as noted
on the unit rating plate, whichever is
greater.
4. After properly elapsed time, the
thermostat may be set to operate the
compressor.
5. Except as required for safety while
servicing – Do not open system
disconnect switch.
Manual 2100-526H
Page
14 of 24
HIGH AND LOW PRESSURE SWITCH
All models covered by this manual are supplied with
a remote reset high pressure switch and low pressure
switch. If tripped, this pressure switch may be reset by
turning the thermostat off then back on again.
NOTE: Defective pressure switches can be replaced
without reclaiming system charge as they are screwed
onto the service port rather than brazed onto the
system.
THREE PHASE SCROLL COMPRESSOR
START UP INFORMATION
Scroll compressors, like several other types of
compressors, will only compress in one rotational
direction. Direction of rotation is not an issue with
single phase compressors since they will always start
and run in the proper direction.
However, three phase compressors will rotate in either
direction depending upon phasing of the power. Since
there is a 50-50 chance of connecting power in such
a way as to cause rotation in the reverse direction,
verification of proper rotation must be made. All three
phase units incorporate a phase monitor to ensure
proper field wiring. See the "Phase Monitor" section
later in this manual.
Verification of proper rotation must be made any time a
compressor is change or rewired. If improper rotation is
corrected at this time there will be no negative impact
on the durability of the compressor. However, reverse
operation for over one hour may have a negative impact
on the bearing due to oil pump out.
NOTE: If compressor is allowed to run in reverse
All three phase ZPS compressors are wired identically
internally. As a result, once the correct phasing
is determined for a specific system or installation,
connecting properly phased power leads to the same
Fusite terminal should maintain proper rotation
direction.
Verification of proper rotation direction is made by
observing that suction pressure drops and discharge
pressure rises when the compressor is energized.
Reverse rotation also results in an elevated sound level
over that with correct rotations, as well as, substantially
reduced current draw compared to tabulated values.
The direction of rotation of the compressor may be
changed by reversing any two line connections to the
7961-061
unit.
See "Phase Monitor", page 16.
rotation for several minutes, the compressor's
internal protector will trip.
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