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© 2016 Emerson Climate Technologies, Inc.
AE5-1412 R1
If the compressor trips more than 4 times per hour (dLn),
the controller will lock out the compressor, requiring a
manual reset or the controller power to be reset. The
controller will display
L44
showing the compressor has
tripped on high DLT and locked out. If parameter dLn,
which is available in the advanced options menu, is set
to 0, the unit will always automatically reset.
6.21.1.1. Low Temp EVI Discharge Line
Temperature Protection Error Handling
In case of DLT failure, the injection valve operates based
on the mid coil and ambient sensor.
If the DLT sensor fails and a mid-coil temperature sensor
is available, the injection valve will be opened based
on the mid coil temperature. If the mid coil sensor fails
in addition to the DLT sensor, the injection valve is
controlled by the ambient temperature.
6.21.2. EVI System Checks (XFAL units only)
An E47 warning code means that the injection valve has
been fully open longer than 3 minutes. An E48 warning
code means that the temperature difference across
the EVI heat exchanger is higher than expected for 3
minutes. These are only warnings, but are likely due to
loss of refrigerant charge or undercharge
6.21.3. Constant Liquid Temperature Mode For
Low Ambient EVI Injection
Subcooling is generally good, but liquid refrigerant
that is too cold can create sizing problems for TXVs.
If the ambient is below 30°F, discharge temperature
is generally well under control and so the controller
disables vapor injection to operate in constant liquid
temperature mode. The low ambient temperature will
generate enough subcooling for the system without the
need for injection. Emerson recommends a balanced
port TXV (or EXV) for low ambient operation.
6.21.4. Low Temperature Units With EVI TXV
Selection
For use with low temperature units with EVI, Emerson
recommends a balanced port TXV because it offers a
wider operating range for floating liquid temperatures.
In addition, the unit liquid line should be insulated since
the liquid line temperature will be lower than the ambient
temperature.
See the table on page 28
for specifics regarding
balanced port sizing recommendations. Applied with the
low temp units it is recommended that a balanced port
expansion valve be used along with a complete review
of the distributor and nozzle (orifice) that is supplied with
the evaporator coil being matched with the applicable
condensing unit. Typically nozzles are selected for
standard TXV sizing using 100°F liquid, with the low
temperature X-Line units those typical selections could
be grossly oversized. See the table on page 28 for the
liquid correction safety factors when selecting those
components.
6.22. Medium Temperature DLT Protection
Medium Temperature units have liquid injection through
the suction line to prevent compressor overheat during
extreme ambient operations. The liquid injection will
keep discharge temperatures below 235°F.
If the discharge temperature goes above 255°F, the
compressor trips and the controller shows an
E44
error.
The compressor cannot turn back on until the discharge
line temperature drops below 170°F and has been off
for at least 3 minutes.
If the compressor trips more than 4 times in an hour
(dLn) on DLT, the controller will lock out the compressor,
requiring a manual reset or the controller power to
be reset. The controller will display
L44
showing the
compressor has tripped on high DLT and is locked
out. If parameter dLn, which is available in the
advanced options menu, is set to 0, the unit will always
automatically reset.
See Section 12 for 86k Thermistor probe resistance
values. Discharge line sensor is 86k, all other
temperature sensors on this unit are 10k.
6.22.1. Medium Temperature DLT Protection Error
Handling
In case of DLT sensor failure, injection is determined by
the mid coil and ambient sensor.
If the DLT sensor fails and a mid-coil temperature sensor
is available, the injection valve will be opened based on
the mid coil temperature. If the mid coil sensor fails in
addition to the DLT sensor, the injection is determined
by the ambient temperature.
