Componentry; High Pressure Switch; Three Phase Scroll Compressor Start Up Information; Phase Monitor - Bard MULTI-TEC W18AAPA Service Instructions Manual

WARNING
!
Electrical shock hazard.
Disconnect VAC power supply before
servicing.
Failure to do so could result in electric shock
or death.

High Pressure Switch

All W**A/W**L wall-mount air conditioner series
models are supplied with a high pressure switch. The
high pressure switch opens at 650 psi.
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.
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 rotation, as well as substantially
reduced current draw compared to tabulated values.
Verification of proper rotation must be made at the
time the equipment is put into service. 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 1 hour may have a
negative impact on the bearing due to oil pump out.
NOTE: If compressor is allowed to run in reverse
rotation for an extended period of time, the
compressor's internal protector will trip.
All three phase 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.
The direction of rotation of the compressor may be
changed by reversing any two line connections to the
unit.

COMPONENTRY

Phase Monitor

Used only on 3-phase equipment, the phase monitor is a
compressor protection device that will prohibit operation
of the compressor if the device senses a possible
reverse-rotation situation due to incorrect phasing. On
a call for compressor (and only compressor), the device
will check incoming phase, check for severe voltage
imbalance and check for proper frequency. Under
nominal conditions, a green LED light will show on the
face of the monitor. If there is improper phasing, voltage
imbalance or frequency deviation, the device will show a
red LED light and prohibit compressor operation.
If a fault condition occurs, reverse two of the supply
leads to the unit. Do not reverse any of the unit factory
wires as damage may occur.

Condenser Fan Operation

NOTE: On models equipped with a low ambient
control (LAC), the condenser fan motor will
have a delayed start until system refrigerant
operating pressure builds up. After starting,
the fan motor may or may not cycle depending
upon ambient conditions. This is normal
operation.
The condenser fan motor on 230/208 volt, one
and three phase, 60 HZ units is a two-speed motor
that comes factory wired on high speed for peak
performance. If ambient conditions permit, it can be
reconnected to low speed (red wire) for lower sound
level. See unit wiring diagram. (This applies to W42,
W48, W60 and W72 models only.)

Low Ambient Control

Modulating head-pressure control that allows full
speed at pressures above 315 psi. Below 315 psi, the
control will slow fan speed—following internal head
pressures—until a minimum RPM is reached (approx
300 RPM). Below this point, the control will shut the
fan completely off until internal pressures rise. The
control is preset from the factory, but should adjustment
become necessary, there is an adjustment screw located
on the bottom of the control behind a weatherproof cap.
One full turn clockwise equals approximately +48 psi.
Manual 2100-665G
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