TM 9-4110-255-14
4-29. DEFROST TIMER TM1 TESTING AND REPLACEMENT.
This task covers:
a. Testing
b. Removal
c. Installation.
INITIAL SETUP
Materials/Parts:
Equipment Conditions:
Lock Washers (2)
Refrigeration unit shut down (para 2-7) and battery
1, Appendix G
disconnected (para 4-35).
Self Locking Nut (2)
Control box cover door raised and latched.
6, Appendix G
Tie Down Strap
General Safety Instructions:
7, Appendix E
Marker tags (7)
WARNING
4, Appendix E
Exposed rotating parts are used in the
refrigeration unit. Personal injury can result if
battery is connected.
a. Testing. (See Figure 1-4.)
(1) Be sure battery has been disconnected then remove two bolts (1) and lock washers (2). Open control
panel (3). Discard lock washers.
(2) Remove and discard tie down strap (4).
(3) Pull defrost timer (5) from relay mounting socket (6).
(4) Using multimeter set to measure continuity, check defrost timer (5) 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 (5) 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 (6) is damaged, replace it.
(7) If no failure was indicated, push defrost timer (5) into relay mount socket (6) and install new tie down strap
(4).
(8) Close control panel (3) and install two new lock washers (2) and bos (1).
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b. Removal.
(1) Be sure battery has been disconnected and remove two bolts (1) and lock washers (2). Open control panel
(3). Discard lock washers.
(2) Cut and discard tie down strap (4).
(3) Pull defrost timer (5) from relay mounting socket (6).
4-73
