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8.0 ACTIVE SYSTEM PROTECTION FEATURES
power to
both
the indoor and outdoor units for 1
minute and then reconnecting power.
NOTE: If the system experiences a high
refrigerant pressure lock-out, the system
should be evaluated to determine the cause
for the high pressure condition and corrective
action taken to eliminate the cause. Possible
causes include excessive refrigerant charge,
a failed indoor blower motor, dirty return air
filter, or a dirty indoor coil (heating mode) or
excessive refrigerant charge, a failed outdoor
motor, or dirty outdoor coil (cooling mode).
8.7 Low Suction Pressure/
Loss of Charge
The Variable Speed Outdoor Control (VSODC)
continuously monitors the Suction Pressure
Transducer input and will protect the compressor
from damage by shutting it down when the suction
pressure drops below 50 PSIG in the cooling
mode and below 15 PSIG in the heating mode. A
low pressure condition can result from inadequate
indoor air-flow, low refrigerant charge, failed
EXV, or a restriction in the refrigerant circuit. The
VSODC will allow the compressor to restart if the
suction pressure rises to 95 PSIG in the cooling
mode and 40 PSIG in the heating mode. A low
refrigerant pressure fault will be ignored for the first
90 seconds of compressor operation and during
the entire defrost cycle to eliminate nuisance faults.
If there are 3 low pressure faults in the same call
for cooling or during 120 minutes of continuous
heating operation, the VSODC will lock the
compressor out and flash a 21L fault code and
the EcoNet
TM
Control Center will display a Low
Refrigerant Pressure Lockout fault on the screen.
If the outdoor ambient is below -10°F [-23°C] in the
heating mode when the lockout occurs, the control
will automatically reset when the outdoor ambient
rises to -10°F [-23°C]. If the outdoor ambient is
above -10°F [-23°C], a manual reset is required
for the VSODU to exit the compressor lock-out
mode and clear the fault. This is accomplished
by disconnecting the electrical power to
both
the
indoor and outdoor units for 1 minute and then
reconnecting power.
NOTE: If the system experiences a low
refrigerant pressure lock-out, the system
should be evaluated to determine the cause
for the low pressure condition and corrective
action taken to eliminate the cause. Possible
causes include low refrigerant charge, failed
indoor blower motor, dirty return air filter, or
a dirty indoor coil in the cooling mode or low
refrigerant charge, a failed outdoor motor, or a
dirty outdoor coil in the heating mode.
8.8 Compressor Shut-
Down Sequence for
High or Low Refrigerant
Pressure Fault
1. The compressor is commanded to operate at
zero (0) RPM for a minimum of 5 minutes.
2. The outdoor EXV will be directed to completely
close for a period of 5 minutes and will then
open up completely.
3. The outdoor fan motor will continue to operate
during the 5 minute compressor off delay.
4. The VSODC and EcoNet
TM
Control Center will
display the applicable fault code.
5. If after 5 minutes cooling or heating demand
persists and the pressure has reached reset
conditions, normal system operation will
resume and the fault codes will be cleared
from the VSODC and EcoNet
TM
Control Center
displays.
6. If after 5 minutes cooling or heating demand
persists and the pressure has not reached
reset conditions, the outdoor fan motor will be
shut down. Once the pressure reaches reset
conditions after the 5 minute delay, normal
system operation will resume.
8.9 Overcurrent and
Current Imbalance
If the compressor current exceeds an acceptable
level for the compressor or inverter, the inverter will
reduce the compressor speed to allow the current
to return to an acceptable level. If there is a current
imbalance between the compressor 3-phase
windings, the inverter will shut the compressor
down for 5 minutes and will lock the compressor
out if there are 3 faults within a single call for
operation.
8.10 Compressor
Operation Outside
Envelope
If the inverter detects that the compressor
motor torque exceeds an acceptable level for
the compressor, the inverter will reduce the
compressor speed to keep the torque at an
acceptable level.
System Protection
