Manual 2100-427
Page 13
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.
