Sumitomo HC-4A, Technical Manual

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Troubleshooting
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8. Read the current draw for each lead, then stop the compressor.
•
A reading of 0 amperes indicates an open circuit.
•
A reading of 10 to 14 amperes (steady state) is normal.
•
A reading slightly higher than 10 to 14 amperes suggests possible minor system
problems, i.e. low-supply voltage, loose electrical connection, etc.
•
A reading of about 68 amperes indicates a mechanically locked rotor. Consult a SCAI
Service Center.
•
A reading of full scale, along with a tripped circuit breaker or a blown control circuit fuse,
means a short circuit in the chassis wiring or motor.
9. Remove the ammeter.
10. Replace the terminal block access cover.
Fan and Circulator
Fan motor and circulator motor checks for winding continuity, resistance and grounding will
isolate most fan motor and circulator motor electrical problems. When the checks indicate a
faulty fan motor or faulty circulator motor, a replacement is needed. Contact a SCAI Service
Center.
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 1/2 hour after
shutdown before removing the cover for maintenance.
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.
Winding Continuity, Grounding and Resistance Checks—Fan and Circulator Motors
Tools required: Ohmmeter or multimeter
#2 Phillips screwdriver.
3 mm (1/8”) flat-blade screwdriver
1. Disconnect the power to the compressor.