TM 9-4110-258-13
4.27 CONTACTOR (POWER RELAY) K5 TESTING AND REPLACEMENT.
This task covers:
a. Testing
b. Removal
c. Installation
INITIAL SETUP
Materials/Parts:
Equipment Conditions:
Lock Washers (4)
Refrigeration unit shut down (para 2.7) and power
6, Appendix G
disconnected.
Marker Tags (10)
Control box cover door raised and latched.
7, Appendix E
General Safety Instructions
WARNING
High voltage and exposed rotating parts are
used in the refrigeration unit. Personal injury
can result if power is connected.
a.
Testing. (See Figure 1-4.)
(1) Be sure power has been disconnected at the source and remove six screws (1). Open control box cover
(2).
(2) Remove defrost timer (para 4.29).
(3) Press and hold plunger (3) during following tests.
(4) Using multimeter set to measure continuity, check auxiliary contact (4) continuity between terminals C and
NO. Continuity should be indicated. If no continuity was indicated, replace auxiliary contact.
(5) Using multimeter set to measure continuity, check each contactor (5) contact continuity between terminals
L1 to T1, L2 to T2, and L3 to T3. Continuity should be indicated. If no continuity was indicated, replace
contactor.
(6) Release plunger (3).
(7) Using multimeter set to measure continuity, check coil continuity between terminals A1 to A2. Continuity
should be indicated. If no continuity was indicated, replace contactor (5).
(8) Using multimeter set to measure continuity, check auxiliary contact (4) continuity between terminals C and
NO. No continuity should be indicated. If continuity was indicated, replace auxiliary contact.
(9) Using multimeter set to measure continuity, check each contactor (5) contact continuity between terminals
L1 to T1, L2 to T2, and L3 to T3. No continuity should be indicated. If continuity was indicated, replace
contactor.
(10) If no failure was indicated, install defrost timer (para 4.29).
(11) Close control box cover (2) and install six screws (1).
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