Sumitomo F-70H, Service Manual

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TROUBLESHOOTING
25
AVOID ELECTRIC SHOCK. Permit only qualified electrical technicians to open
electrical enclosures, to perform electrical checks or to perform tests with the
power supply connected and wiring exposed. Failure to observe this warning
can result in serious injury or death.
AVOID ELECTRIC SHOCK. Disconnect the power to the compressor before
troubleshooting the electrical components.
AVOID INJURY FROM BURNS. During operation, some surfaces under the
compressor’s cover become hot. Allow the compressor to cool for ½ hour after
shutdown before removing the cover for maintenance.
PRESERVE YOUR WARRANTY. Modification to equipment without the
consent of the manufacturer will void the warranty.
Compressor Capsule
Compressor motor checks for winding continuity, resistance and grounding will isolate most
motor electrical problems. When the checks indicate a faulty compressor, a replacement
is needed. Contact a Service Center.
Winding Continuity, Grounding and Resistance Checks
Tools required: Ohmmeter or multimeter
#2 Phillips screwdriver
The following electrical measurements to check the compressor motor may be made either at
the compressor terminals or at the motor contactor.
1. Disconnect the power to the compressor.
2. Remove the cover, side panels and rear panel from the compressor.
3. Remove the terminal box cover from the side of the compressor motor to expose the three
terminals T
1,
T
2
and T
3
. It is not necessary to remove the wires from their terminals.
4. With an ohmmeter, check the resistance across pairs of compressor terminals. Line to line
motor resistance for the F-70H compressor capsule should be about 2.27 ± 10% ohms, at
room temperature. Line to line motor resistance for the F-70L compressor capsule should
be about 0.56 ± 10% ohms at room temperature.
If there is no continuity, there is an open
circuit in the motor windings. Consult a Service Center. If the resistance is less, there is a
short circuit in the motor. Consult a Service Center.
5. With the ohmmeter, check for continuity between the motor windings and one of the
unpainted tubes entering the compressor capsule. Use the three compressor terminals and
one of the copper tubes from the compressor. If there is continuity, there is a short circuit to
ground in the motor windings. Consult a Service Center.