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8.0 ACTIVE SYSTEM PROTECTION FEATURES
System Protection
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 outdoor motor, or dirty outdoor coil.
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. A low pressure con
-
dition can result from inadequate indoor air-flow, low
refrigerant charge, failed EXV, or a restriction in the
refrigerant circuit. The VSODC will allow the com
-
pressor to restart if the suction pressure rises to 95
PSIG. A low refrigerant pressure fault will be ignored
for the first 90 seconds of compressor operation 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.
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.
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 fan motor will continue to operate
during the 5 minute compressor off delay.
3. The VSODC and EcoNet
TM
Control Center will
display the applicable fault code.
4.
If after 5 minutes cooling 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.
5. If after 5 minutes cooling 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.
