Thermo King 914 724, Manual

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Electric Standby Mechanical Diagnosis (Rev. 1/99)
84
Unit in vacuum. Frost on
expansion valve only Ice plugging expansion valve orifice Apply hot wet cloth to expansion
valve. Moisture indicated by
increase in suction pressure.
Replace drier
Plugged expansion valve strainer Clean strainer or replace expansion
valve
Sensor bulb lost charge Replace expansion valve
ELECTRIC STANDBY SERVICE CHECKS
1. Motor does not run 1. Check for power at source
2. Check for power at plug
3. Check for power at compressor contactor
4. Check for power at overload terminals (contactor
closed)
5. Check for power at motor terminals
2. Power at motor terminals but motor does not run 1. Replace motor
3. Motor hums but does not run 1. Check for locked rotor
2. Check for worn bearings. Replace if necessary
3. Check for locked compressor and repair
4. Power source for single phasing
5. Check capacitors (on single phase units)
4. Check transformer 1. Check for power output 16 Vac, 12 volt system
5. Check rectifier 1. Check for rectifier output 14 Vdc, 12 volt system
CONDITION POSSIBLE CAUSE REMEDY