Manual 2100-769A
Page
30 of 50
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 (call for cooling) is present at the
phase monitor and phases are correct, the green LED
will light.
NOTE:
The phase monitor will not show phase reversal
until the compressor is energized during a call
for cooling or heat pump operation.
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.
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. Switching to heating cycle at 75°F or higher
outside temperature may cause a nuisance trip
of the remote reset high pressure switch. Turn
thermostat off, then on to reset the high pressure
switch.
3. Heat pump wall thermostats perform multiple
functions. Be sure that all function switches are
correctly set for the desired operating mode before
trying to diagnose any reported service problems.
4. Check all power fuses or circuit breakers to be sure
they are the correct rating.
5. Periodic cleaning of the outdoor coil to permit full
and unrestricted airflow circulation is essential
.
6. Annual maintenance is required to make sure that
all of the systems are functioning properly.
a. Check to make sure that the drains are not
obstructed in any way.
b. Remove any debris in the condenser section of
the unit.
c. Inspect and wash outdoor coils as necessary.
7. All motors are sealed and require no oiling.
Sequence of Operation
Cooling Stage 1
Circuit R-Y1 makes at thermostat pulling in compressor
contactor, starting the compressor and outdoor motor.
(See
NOTE
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.
Cooling Stage 2
Circuit R-Y1 & Y2 makes at the thermostat energizing
the 2nd stage solenoid in the compressor. The default
position of the compressor staging solenoid is non-
energized. The compressor will run at low capacity until
this solenoid is energized.
Heating Stage 1
A 24V solenoid coil on reversing valve controls heating
cycle operation. Two thermostat options, one allowing
“Auto” changeover from cycle to cycle and the other
constantly energizing solenoid coil during heating
season and thus eliminating pressure equalization
noise except during defrost, are to be used. On “Auto”
option, a circuit is completed from R-B and R-Y1 on
