SERVICING
Do not use a low voltage output instrument such as a volt- ohmmeter.
COMPRESSOR GROUND TEST
3.If a ground is indicated, then carefully remove the com- pressor terminal protective cover and inspect for loose leads or insulation breaks in the lead wires.
4.If no visual problems indicated, carefully remove the leads at the compressor terminals.
WARNING
Damage can occur to the glass embedded terminals if the leads are not properly removed. This can result in terminal and hot oil discharging.
Carefully retest for ground, directly between compressor terminals and ground.
5. If ground is indicated, replace the compressor.
S-17C UNLOADER TEST PROCEDURE
Anominal
UNLOADER SOLENOID
(Molded Plug)
Unloader Test Procedure
If it is suspected that the unloader is not working, the following methods may be used to verify operation.
1.Operate the system and measure compressor current. Cycle the unloader ON and OFF at 10 second intervals. The compressor amperage should go up or down at least 25 percent.
2.If step one does not give the expected results, shut unit off. Apply 18 to 28 volt ac to the unloader molded plug leads and listen for a click as the solenoid pulls in. Remove power and listen for another click as the unloader returns to its original position.
3.If clicks can’t be heard, shut off power and remove the control circuit molded plug from the compressor and measure the unloader coil resistance. The resistance should be 32 to 60 ohms, depending on compressor temperature.
4.Next check the molded plug.
A.Voltage check: Apply control voltage to the plug wires (18 to 28 volt ac). The measured dc voltage at the female connectors in the plug should be around 15 to 27 vdc.
B.Resistance check: Measure the resistance from the end of one molded plug lead to either of the two female connectors in the plug. One of the connec- tors should read close to zero ohms while the other should read infinity. Repeat with other wire. The same female connector as before should read zero while the other connector again reads infin- ity. Reverse polarity on the ohmmeter leads and repeat. The female connector that read infinity previously should now read close to zero ohms.
C.Replace plug if either of these test methods doesn’t show the desired results.
S-17D OPERATION TEST
If the voltage, capacitor, overload and motor winding test fail to show the cause for failure:
HIGH VOLTAGE!
Disconnect ALL power before servicing or installing. Multiple power sources may be present. Failure to do so may cause property damage, personal injury or death.
1.Remove unit wiring from disconnect switch and wire a test cord to the disconnect switch.
NOTE: The wire size of the test cord must equal the line wire size and the fuse must be of the proper size and type.
2.With the protective terminal cover in place, use the three leads to the compressor terminals that were discon- nected at the nearest point to the compressor and connect the common, start and run clips to the respec- tive leads.
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