TK 61753-2-MM-EN
23
Unit Description
General Information
This Thermo King A-Series unit is a one piece, self-contained, diesel/electric powered cooling/heating trailer unit. The
unit mounts on the front of the trailer with the evaporator extending through an opening in the front wall. It features a
fully programmable microprocessor controller designed exclusively for transport refrigeration applications, all-new
DDE (Diesel Direct Electric) architecture, a quiet running Thermo King diesel engine, and a Thermo King X430
reciprocating compressor.
Figure 1. Thermo King A-Series Unit Shown
Design Features
• A-Series Controller
• TouchLog™ Data Logger
• Electronic Throttling Valve (ETV)
• EMI-3000
• TK TracKing
Electronic Throttling Valve (ETV)
The Electronic Throttling Valve (ETV) is standard on the these units. The ETV is a variable position valve operated by a
stepper motor. The ETV is located in the suction line between the accumulator and the suction vibrasorber. The ETV
system also uses discharge and suction pressure transducers, and a hot gas bypass valve.
The ETV has two internal coils. The microprocessor operates the valve by energizing the coils with a variable frequency
AC signal. The valve position can be monitored with the Gauges Menu. Zero (0) indicates the valve is fully closed and
800 indicates the valve is fully open.
The microprocessor tests the ETV if required when the unit is started. Alarm Code 89 indicates the refrigeration system
pressures did not respond as expected during the test. This may be caused by a malfunction of the ETV or by a
refrigeration system problem such as low refrigerant level, a frozen expansion valve, or a restriction in suction line. The
microprocessor ignores the test results if the box temperature or the ambient temperature is below -12 C (10 F). The
ETV test can also be performed using the Service Test Mode.
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