Thermo King SR-2 SmartReefer2, Diagnostic Manual

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Section 5 – SR-2 Diagnostics
89 CHECK ELECTRONIC THROTTLING VALVE CIRCUIT
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Alarm Type Check or Shutdown Alarm
Associated Alarm
Codes
Component Description and Location
The ETV is located in the suction line and is accessible from the rear of the unit.
Circuit Description
How Alarm is Set
Alarm can be set during the non-running and running phases of the engine start routine. During the non-running
phase the ETV driver output error conditions are checked (valve electrical test). During the first phase of the
running test, the unit is operated with the ETV mostly closed. Correct ETV position is confirmed by a drop in
suction pressure. During the second phase of the running test, the ETV is opened. Correct ETV operation is
confirmed by a rise in suction pressure.
The electrical test is performed before every engine or motor start. The running test is only performed when the
unit restarts after a shutdown or prevent alarm or if the microprocessor suspects a problem with either or both of
the refrigerant pressure transducers. The running test is also performed when an engine start occurs during a Pre-
trip Test.
How Alarm is Cleared
This alarm is cleared manually.
Diagnostic Procedure
1. Check suction and discharge pressures with unit not running, to determine if refrigerant charge appears
adequate.
2. Check electrical operation of electronic throttling valve circuit, using Service Procedure G03A.
3. If the electronic throttling valve appears to function electrically, check the refrigeration system for low
refrigerant, a frozen expansion valve, or a severe restriction in the suction side of the system.
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02 February 2005