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Test Procedure for a Short Circuit to Ground (Ground Fault)
1. Disconnect all electrical power to the system, making sure all power legs are open.
2. Remove the protective terminal cover. Inspect for evidence of overheating at any connection.
Overheating is an indication that a compressor motor problem exists. Disconnect all leads
from the terminal pins.
3. Check the compressor for a ground fault using an ohm meter or a high potential ground
tester. Connect one lead to the copper suction line and connect the other lead to one of the
terminal pins. Repeat this procedure for the two remaining terminal pins. If the instrument
indicates any resistance less than 2 mega ohms between any pin and the suction line
(compressor housing), a ground fault exists.
4. If a ground fault exists, replace the compressor. Do not reconnect the compressor or re-use
any leads or terminal connectors that exhibit signs of overheating.
Test Procedure for Continuity and Proper Resistance
1. If no ground fault has been found, determine if there is an open or short circuited motor
winding or if the thermal protector is open.
2. Allow time for the thermal protector to reset. This may take as long as an hour for internal
type thermal protectors.
3. For single phase compressors, test the continuity of the start winding by measuring between
terminal pins C and S. Test the continuity of the main winding by measuring between terminal
pins C and R. If there is no continuity in either winding, replace the compressor.
4. For three phase compressors, test the continuity of the windings by measuring between each
pair of terminal pins: 1-2, 2-3 and 1-3. If there is no continuity between any set of terminal
pins, replace the compressor.
5. If continuity is found in all motor windings, measure the resistance (ohms) of the windings.
6. For single phase compressors, measure between each pair of terminal pins: C-S, C-R and
S-R. The sum of the resistance measured between C-S and C-R should equal the resistance
measured between S-R, plus or minus a small deviation. Proper resistance may be confirmed
by comparing the measured resistance to the resistance specifications for specific compressor
models. If the resistance is not correct, replace the compressor. If the specifications are not
found on the ice machine, please contact the factory.
7. For three phase compressors, measure between each pair of terminal pins: 1-2, 2-3 and 1-3.
The resistance measured between each pair of pins should always be greater than zero and
within 10% of one another. Proper resistance may be confirmed by comparing the measured
resistance to the resistance specifications for specific compressor models. If the resistance is
not correct, replace the compressor. If the specifications are not found on the ice machine,
please contact the factory.
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