Unit Description 5-22
Zone 1 on COOL, Zone 2 on COOL and Zone 3 on HEAT
NOTE: The following example shows a DE-3, TCI-3 or SPECTRUM-3 Multi-Temp system for a 3 compartment trailer. The
operation of a DE-2, TCI-2 or SPECTRUM-2 system for a 2 compartment trailer is similar.
See refrigeration system diagram on the previous page. The condenser inlet solenoid is closed so high pressure refrigerant vapor
leaves the compressor and flows through the hot gas line and the open HGS3 hot gas solenoid to the Zone 3 evaporator. There
the refrigerant heats the evaporator and condenses into high pressure liquid. Because the SLS3 suction line solenoid is closed,
the liquid refrigerant flows through the LRCV3 liquid return check valve and liquid line to the LLS and LLS2 liquid line
solenoids.
The LLS liquid line solenoid is open so the refrigerant flows through the Zone 1 expansion valve into the Zone 1 evaporator.
There the liquid refrigerant cools the evaporator as it evaporates into low pressure vapor. The refrigerant returns to the compressor
through the SLCV suction line check valve and the accumulator.
The LLS2 liquid line solenoid is open so the refrigerant flows through the Zone 2 expansion valve into the Zone 2 evaporator.
There the liquid refrigerant cools the evaporator as it evaporates into low pressure vapor. The refrigerant returns to the compressor
through the SLS2 suction line solenoid, the suction line, the SLCV2 suction line check valve and the accumulator.
Defrost
Defrost can be manually initiated, or automatically by the controller defrost timer or controller Demand Defrost algorithm. A
demand defrost occurs when the difference between the return air temperature, discharge air temperature and evaporator coil
temperature becomes excessive.
Defrost can be initiated any time the evaporator coil temperature is below 7 C. When a defrost cycle is initiated, the controller
energises the damper motor or solenoid, or turns the remote evaporator fan off. The host unit operates in low speed when a zone
is in Defrost.
The unit remains in defrost until the evaporator coil temperature increases to 14 C. If the evaporator coil temperature does not
rise to 14 C within the defrost duration time limit (30 or 45 minutes), the controller terminates defrost. The evaporator then returns
to operation based on controller demand.
SLXe Spectrum and SLXi Spectrum PTC operation mode
This new function is compatible only with specific redesigned trailer remote evaporators showing the
indication “PTC Precision Temperature Control”
The new trailer remote evaporators introduce a new pulsing Liquid Line Solenoid (LLS) ref. 61-6521 to improve temperature
control. The first trailer remote evaporator produced with this new pulsing LLS is:
• S3 Trailer remote evaporator serial number = GLW1053199
• Start date = 12/10/2015
Any trailer remote evaporators produced from this date will have the pulsing LLS as standard.
Important Points:
This new function is available in conjunction with controller software F020 or later. It is factory set to DISABLED and must
be activated during PDI.
How to Activate PTC:
1. First, you have to make PTC viewable in the mode menu:
a. Enter Guarded Access Menu,
b.Go to Programmable Features,
c. Change Precision Temperature Control (disabled) to ENABLED, (See in Blue Bold on the following flowchart).
Precision Temperature Control
Control Revision F020 and later
HMI Revision 75C1 and later
Choices ENABLED or DISABLED
Factory Set DISABLED
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