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The controls found in the RD17AZ outdoor units
are designed to prevent the system from operating
in under conditions that could be harmful to the
compressor and inverter. The Universal Outdoor
Control (UODC) and Power Inverter continuously
monitor multiple sensors, current, and voltage and
will modify the compressor speed or completely
shut the system down to protect the compressor
and/or inverter if harmful operating conditions are
sensed. This process is called Active System
Protection. Sections 8.1 – 8.14 give a brief
description of the different forms of protection that
are provided. Refer to the Econet help pages on
the Rheem website for further troubleshooting and
diagnostics.
8.1 Minimum Run Timer
A minimum run time of 5 minutes is maintained by
the VSODC to minimize short cycling which can be
harmful to the compressor.
8.2 Oil Return Cycle
When the system has been operating at significantly
reduced capacity for an extended period of time,
the Universal Outdoor Control (UODC) will signal
the Inverter to speed the compressor up to 70%
capacity to help bring any oil that has accumulated
in the indoor coil and refrigerant lines back to the
compressor sump
.
8.3 Low Suction Pressure
/
Loss of Charge
The Universal Outdoor Control (UODC) 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 [345 kPa] in the cooling mode and
below 15 PSIG [103 kPa] in the heating mode. A
low pressure condition can result from inadequate
indoor air-flow, low refrigerant charge or a restriction
in the refrigerant circuit. The UODC will allow the
compressor to restart if the suction pressure rises
to 95 PSIG [655 kPa] in the cooling mode and
40 PSIG [276 kPa] 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 UODC will lock the compressor out
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.
8.4 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 UODC and EcoNet
TM
Control Center will
display the applicable fault code.
4. 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 UODC and EcoNet
TM
Control Center
displays.
5. 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.
8.0 ACTIVE SYSTEM PROTECTION FEATURES
System Protection
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