Manual 2100-640I
Page
20 of 32
HIGH PRESSURE SWITCH
All W**A/W**L wall mounted air conditioner series
models are supplied with a remote reset for the high
and low pressure switch. If tripped, this pressure
switch may be reset by turning the thermostat off then
back on again
.
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.
PHASE MONITOR
All units with three phase scroll compressors are
equipped with a three phase line monitor to prevent
compressor damage due to phase reversal.
The phase monitor in this unit is equipped with two
LEDs. If the Y signal is present at the phase monitor
and phases are correct, the green LED will light.
If phases are reversed, the red fault LED will be lit and
compressor operation is inhibited.
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:
Certain models may be equipped with a
low ambient control (LAC), and if so, 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 wiring diagram. (
This applies to W42, W48,
W60 and W72 models only.
)
50 HZ models must have fan wired on low speed.
These models are factory wired on low speed.
SERVICE HINTS
1. Caution owner/operator to maintain clean air
filters at all times and also not to needlessly close
off supply and return air registers. This reduces
airflow through the system, which shortens
equipment service life as well as increasing
operating costs.
2. Check all power fuses or circuit breakers to be sure
they are the correct rating.
3. Periodic cleaning of the outdoor coil to permit full
and unrestricted airflow circulation is essential
.
SEQUENCE OF OPERATION
COOLING – Circuit R-Y1 makes at thermostat pulling
in compressor contactor, starting the compressor and
outdoor motor. (See
NOTE
above under Condenser
Fan Operation concerning models equipped with low
ambient control.) The G (indoor motor) circuit is
automatically completed by the thermostat on any call
for cooling operation or can be energized by manual
fan switch on subbase for constant air circulation.
On a call for heating, circuit R-W1 makes at the
thermostat pulling in heat contactor for the strip heat
and blower operation. On a call for second stage heat,
R-W2 makes bringing on second heat contactor, if so
equipped.
VENT CONNECTION PLUG
All units are equipped with a vent connection plug in
the side of the control panel for the different ventilation
packages to plug in to. If the compressor will not start
and there is no "Y1" at the compressor control module,
