Thermo King SR-2 SmartReefer2, Diagnostic Manual

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Section 3 – SR-2 Software Description
Continuous Mode OptiSet Features -
Fresh Ranges with ETV and Modulation
On
The features shown below can be modified in
Continuous Mode operation with Fresh ranges on
units equipped with ETV and with Modulation turned
on. Continuous Mode features are different for
Frozen ranges or for Fresh ranges on units that are
not equipped with ETV or if Modulation is turned Off.
FreshSet™
FreshSet is an additional set of configurable
parameters within the OptiSet program tailored for
Fresh Produce. It is applicable for ETV based units
using the Continuous Run mode.
FreshSet allows modulation temperature control to
be configured with a Floor Limit and High Speed
Modulation Ceiling (temperature band).
The refrigeration unit will operate in low speed to
keep discharge air temperature and return air
temperature within these bands. If the refrigeration
unit is unable to maintain the band it will
automatically force the unit into high speed
operation until the temperature band requirements
are met. High ambient temperatures, poor trailer
insulation and product loaded warm are potential
causes that could force the unit to run in high speed
for a period of time.
Modulation Control
Micro Rev
All
HMI Rev
All
Choices Off or On
Factory Set On
Exceptions
Description This feature allows Modulation to be
turned On or Off for the selected range.
An ETV (Electronic Throttling Valve) capable of
opening and closing incrementally is installed
between the evaporator
and the compressor. If
modulation is turned On, the ETV is controlled
directly by the microprocessor. As the temperature
approaches setpoint, the ETV begins to close,
throttling the suction gas returning to the compressor
and thus reducing cooling capacity. As the box
temperature approaches setpoint, the ETV becomes
more nearly closed. This feature provides very
smooth and steady temperature control. Modulation
is only operational in Continuous mode.
The normally closed hot gas solenoid is opened
during modulated cool when the temperature is very
close to setpoint. This diverts hot gas from the
compressor discharge line, through the open hot
gas solenoid to the evaporator distributor, in order to
further reduce cooling capacity and prevent the
compressor from operating in a vacuum.
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31 January 2005