TM 9-4120-407-14
3-35. HEATER THERMOSTAT TESTING AND REPLACEMENT.
b. Testing
a. Removal
c. Installation
This task covers:
lNlTIAL SETUP
Tools
Equipment Conditions:
Remove top panel. See para 3-14.
Service Refrigeration Unit Tool Kit
(Item 1, Appendix B)
Materials/Parts
Self locking nuts, Qty 2 (Item 21, Appendix G)
Marker Tag (Item 2, Appendix E)
a. Removal.
(1) Tag and disconnect leads.
(2) Remove two self locking nuts (1), screws (2), flat washers (3), and thermostatic switch (4).
Discard self locking nuts.
Figure 3-54. Thermostatic (Heater Cutout) Switch
b. Testing.
(1) With thermostat at room temperature, use multimeter set on the lowest OHMS scale to check for
continuity between terminals 1 and 2. If continuity is not indicated between terminals, replace the
thermostat.
(2) For full operational test of thermostat use an external heat source. Thermostat should open
(no continuity across terminals) at temperature increase of 194 F 9 (90 C 5) and close at
temperature decrease of 142 F 16 (61 C 9). If defective, replace thermostatic switch.
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