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Service Reference Manual TROUBLESHOOTING
9-3
SRM-HW/HWC 8/99
2. Set an ohm meter to the lowest possible setting. On a note pad,
write the following: “C to ground”, “S to ground” and “R to ground.”
3. Using the ohm meter, check for continuity between C terminal on the
fusite plug and the case of the compressor (a spot may have to be
cleaned on the compressor to get a good reading.) Record what was
observed on the note pad next to the heading “C to ground”. Do the
same to the other two terminals and record the findings in the proper
places.
4. If any sign of continuity between any of the terminals and ground was
observed, recheck the terminal to confirm that the readings were
correct. Any indication of continuity between any of the terminals and
ground would point to an internal winding being shorted to the
compressor case. This suggests that the compressor has an internal
failure and it would need to be replaced.
5. If no continuity is noted between any of the terminals and ground, the
compressor must be checked out further.
Checking Windings
The following test is used to check the condition of the internal start and
run windings.
1. Write the following down: “C to S”, “C to R” and “S to R.”
2. Using the volt/ohmmeter, measure the resistance between terminals
C and S. Record the findings on the note pad in the correct place.
Measure and record the resistance between the remaining terminals
in the same manner.
The following examples show how this information can be used to deter-
mine if there is an internal failure.
Example #1
C to S (Common through Start Windings) 3.5 ohms
C to R (Common through Run Windings) 1.5 ohms
S to R (Start Windings through Common and Run Windings) 5.0 ohms
A resistance measurement between C to S shows that there is continuity
between the common and start terminals. The reading between terminals
C and R proves that there is continuity between the terminals through the
windings. The resistance recorded between S and R is actually a reading
of the entire circuit within the motor (S through C to R).
A determination of the condition of the motor windings can be made with
the information just collected. The following steps show how this is done.
1. Add the readings from “C to S” and “C to R.”
C to S (3.5 ohms) + C to R (1.5 ohms) = 5 ohms