Manual 2100-348
Page 15
START UP
IMPORTANT INSTALLER NOTE
For improved start up performance wash the indoor coil
with a dish washing detergent.
CRANKCASE HEATERS
These units are not provided with crankcase heat. These
units utilize scroll compressors which do not require
crankcase heat in this application.
HIGH PRESSURE SWITCH
The models are supplied with a remote reset high
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 one 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 several minutes, the compressor’s
internal protector will trip.
All three phase ZR3 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.
SERVICE HINTS
1. Caution homeowner to maintain clean air filters at all
times. Also, not to needlessly close off supply and
return air registers. This reduces air flow 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. Check all power fuses or circuit breakers to be sure
they are the correct rating.
4. Periodic cleaning of the outdoor coil to permit full
and unrestricted airflow circulation is essential.
SEQUENCE OF OPERATION
COOLING
– Circuit R-Y makes at thermostat pulling in
compressor contactor, starting the compressor and
outdoor motor. The G (indoor motor) circuit is
automatically completed on any call for cooling operation
or can be energized by manual fan switch on subbase of
constant air circulation. On all 230 volt units there is a
one minute off delay on the blower motor. 460 volt
models do not have an off delay.
COMPRESSOR CONTROL MODULE
The compressor control module is standard on the models
covered by this manual. The compressor control is an
anti-short cycle/lockout timer with high and low pressure
switch monitoring and alarm relay output.
Adjustable Delay On Make And Break Timer
On initial power up or any time power is interrupted to
the unit the delay on make period begins which will be 2
minutes plus 10% of the delay on break setting. When
the delay on make is complete and the high pressure
switch (and low pressure switch if employed) is closed,
the compressor contactor is energized. Upon shutdown
the delay or break timer starts and prevents restart until
the delay on break and delay on make periods have
expired.
During routine operation of the unit with no power
interruptions the compressor will operate on demand with
no delay.
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