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TK 61555-2-MM-EN
Operating Modes
The microprocessor uses a complex program to determine which operating mode the unit
should be in. Therefore, it is difficult to predict which operating mode the unit should be in by
comparing the setpoint to the box temperature.
The diesel engine operates at either low speed or high speed as determined by the
microprocessor. The unit will Cool or Heat in either high or low speed. The unit will Defrost in
low speed only. Heat and Defrost consists of hot gas delivered to the evaporator coil distributor.
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The microprocessor will select the operating mode from the following:
•
High Speed Cool
•
Low Speed Cool
•
Low Speed Heat
•
High Speed Heat
•
Defrost
N
No
otte
ess::
1. High Speed Heat is locked out if controller setpoint is below Fresh/Frozen temperature
setting
2. During Cycle Sentry Operation:
•
After initial unit start-up and unit pull-down to setpoint, the controller limits Low
Speed Cool operation when the controller setpoint is below Fresh/Frozen
temperature setting. On increasing compartment temperature, the unit operates in
Low Speed Cool for a maximum of 8 minutes in an attempt to reach setpoint. If
setpoint is not reached within 8 minutes, the unit will operate in High Speed Cool
until setpoint is reached
•
Unit mode is Null when the engine temperature and battery are satisfied.
•
Null mode if setpoint is below Fresh/Frozen temperature setting.
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The microprocessor will select the operating mode from the following:
•
Cool
•
Null
•
Hot Gas Heat
•
Full Heat
•
Defrost
N
No
otte
ess::
1. Null mode ONLY if controller setpoint is below Fresh/Frozen temperature setting
2. Null mode if setpoint is below Fresh/Frozen temperature setting.
3. During Cycle Sentry Operation:
•
After initial unit start-up and unit pull-down to setpoint, the controller limits Low
Speed Cool operation when the controller setpoint is below Fresh/Frozen
temperature setting. On increasing compartment temperature, the unit operates in
Low Speed Cool for a maximum of 8 minutes in an attempt to reach setpoint. If
setpoint is not reached within 8 minutes, the unit will operate in High Speed Cool
until setpoint is reached
•
Unit mode is Null when the engine temperature and battery are satisfied.
Defrost
Frost gradually builds-up on evaporator coils as a result of normal operation. The unit uses hot
refrigerant to defrost the evaporator coils. Hot refrigerant gas passes through the evaporator coil
and melts the frost. The water flows through collection drain tubes onto the ground. The
methods of Defrost initiation are Automatic and Manual.
