TM 9-4110-258-13
4.29 DEFROST TIMER TM1 TESTING AND REPLACEMENT.
This task covers:
a. Testing
b. Removal
c. Installation
INITIAL SETUP
Materials/Parts:
Equipment Conditions:
Self Locking Nut (2)
Refrigeration unit shut down (para 2.7) and power
8, Appendix G
disconnected.
Tie Down Strap
Control box cover door raised and latched.
23, Appendix E
Marker Tags (7)
General Safety Instructions:
7, Appendix E
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 and discard tie down strap (3).
(3) Pull defrost timer (4) from relay mounting socket (5).
(4) Using multimeter set to measure continuity, check defrost timer (4) continuity between terminals 1 to 7.
Continuity should be indicated. If no continuity was indicated, replace defrost timer.
(5) Using multimeter set to measure continuity, check defrost timer (4) continuity between terminals 4 to 7 and
6 to 9. No continuity should be indicated. If continuity was indicated, replace defrost timer.
(6) If relay mounting socket (5) is damaged, replace it.
(7) If no failure was indicated, push defrost timer (4) into relay mount socket (5) and install new tie down strap
(3).
(8) Close control box cover (2) and install six screws (1).
b.
Removal.
(1) Be sure power has been disconnected at the source and remove six screws (1). Open control box cover
(2).
(2) Remove and discard tie down strap (3).
(3) Pull defrost timer (4) from relay mounting socket (5).
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