Schreiber Chillers Modular Chillers - Manual (Page 31)

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7. If #6 indicated no visible problem, carefully remove the leads at the compressor terminals. CAUTION:
Damage can occur to the glass embedded terminals at this point if the leads are not properly removed,
which can result in the terminal venting and hot oil discharging. No ignition, however, can occur if all
power is disconnected and no external ignition source is present.
8. Repeat #5 testing, carefully checking for ground, directly between each compressor terminal (C, S, &R)
and ground.
9. If once again a ground is indicated, proceed to properly replace the compressor, as it has failed and
cannot be repaired.
10. It is important to note that a volt-ohmmeter may be used only to check resistance and/or continuity of
the motor windings. This may be done as follows:
(a) For internal overload protected motor-compressor, the overload is located between the common
terminal of the compressor and the common motor lead inside the compressor. If the
resistance reading between Common and Start or Common and Run is open (infinity) and the
resistance reading between Start and Run indicates winding Resistance Values in the
Tecumseh Hermetic Compressor Service Data Book, then the internal protector is open and
time must be allowed for it to reset. Any Common and Start, Common and Run, and Start and
Run resistance reading must be within the values shown in Tecumseh Hermetic Compressor
Service Data Book. Three phases internal overloads open all three phases. Therefore, allow
time for reset.
(b) For external overload protected motor-compressors, the continuity of the overload may be
checked. The resistance of all winding may also be checked, i.e., C-S, C-R, and S-R.
(c) Any lack of continuity (other than test indicating an open internal protector) or improper
resistance, indicates a faulty or damaged motor and the compressor must be properly replaced,
as it has failed and cannot be repaired.
If the above indicated no problem with the compressor, then carefully reconnect the leads to the proper
compressor terminals (C,S, &R); correctly replace the terminal PROTECTIVE COVER, gasket (if required), and
the bale strap.
Then proceed to conduct similar ground and continuity test from the three lead connection points which you
previously, disconnected, forward toward the incoming power connections, to find the electrical problems. DO
NOT reset the ground fault protective device until you have located and corrected the problem. Refer to the Unit
Wiring Diagram and Service Manuel for the proper procedure and wiring checkout.
The text of step-by-step procedures uses language and symbols which refer to the electrical supply as single
phase. Three-phase equipment should be given equally cautious consideration when service is necessary.
Again, we want to stress that it is essential that WHENEVER ELECTRIC POWER is applied to the motor-
compressor, the terminal PROTECTIVE COVER must be properly in place.
Servicing refrigeration and air conditioning systems can be dangerous, and the personnel servicing such
equipment should exercise extreme caution in all respects. The precautions discussed in this bulletin deal only
with those dangers associated with VENTING TERMINALS.