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Manual 2100-455A
Page 18 of 25
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 rotations, as well as, substantially reduced
current draw compared to tabulate values.
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 compressors are equipped with
a 3 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.
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 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. The 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.
SEQUENCE OF OPERATION
COOLING STAGE 1 – 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.
COOLING STAGE 2 – Circuit R-Y1 makes at the
thermostat energizing the 2nd stage solenoid in the
compressor. Default position is not energized.
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-W1 and
R-Y on each heating “on” cycle, energizing reversing
valve solenoid and pulling in compressor contactor
starting compressor and outdoor motor. R-G also make
starting indoor blower motor. Heat pump heating cycle
now in operation. The second option has no “Auto”
changeover position, but instead energizes the reversing
valve solenoid constantly whenever the system switch on
subbase is placed in “Heat” position, the “B” terminal
being constantly energized from R. A thermostat demand
for Stage 1 heat completes R-Y circuit, pulling in
compressor contactor starting compressor and outdoor
motor. R-G also make starting indoor blower motor.
HEATING STAGE 2 – Circuit R-Y2 makes at the
thermostat energizing the 2nd stage solenoid in the
compressor.
COMPRESSOR CURRENT & PRESSURE
CONTROL MODULE
The compressor control module monitors compressor
current and pressure and prevents internal overload trips
due to low voltage or extremely high ambient
temperatures by de-energizing the full capacity
compressor solenoid. The control monitors current to the
compressor and discharge pressure. If current is sensed
that is in excess of 93% of the compressor, maximum
continuous current rating or pressure is sensed greater
than 525 PSI, the compressor control module de-
energizes for a time as determined by the time
potentiometer on the compressor control module. This
will drop the current draw and pressure and allow the
compressor to run at 75 percent of capacity rather than
not at all. Once the time period has elapsed the full
capacity compressor solenoid will re-energize and try
again to run at full capacity. If the pressure or current is
exceeded again, the coil will again de-energize. This
sequence will repeat until the ambient temperature drops
or the line voltage increases enough that the trip values
are not exceeded.
The relay on the compressor control module is a single
pole double throw relay. The full capacity compressor
solenoid connects to the common terminal of the relay.
Once current is sensed by the compressor control module,
the relay closes and the second stage cooling call (if
present) is sent to the full capacity compressor solenoid.
This sequence prevents damage to the full capacity
compressor solenoid by ensuring that the solenoid is not
energized when the compressor is not running. A brief
time delay in this sequence also prevents locked rotor
amperage during start-up from tripping the device and
engaging the time delay period.