TM 9-4120-402-14
4-45. HEATER CUTOUT (THERMOSTAT) SWITCH (S4). - continued
b. Test.
(1) Tag and unsolder wire leads from heater cutout (thermostat) switch (1).
(2) With heater cutout (thermostat) switch (1) at room temperature, use a multimeter to check continuity between
terminals (4 and 5). If no continuity is indicated, replace the switch.
NOTE
For full operational test of switch, use an external heat source. Switch should open (no
continuity) between terminals (4 and 5) at temperature increase of between 1850 and 203 (850
F
to 950C) and close again at temperature decrease of between 1260F and 158 (520C and 700C).
F
(3) Cut heat shrink tubing to approximately three-quarter inch (1.9 cm) long.
(4) Slip heat shrink tubing on ends of wires to be soldered.
(6) Slip heat shrink tubing in place over solder connections and shrink tubing. (See paragraph 4-26.)
c. Replace.
(1) Remove two sets of screws (2), lock washers (3), and flat washers (4).
(2) Carefully pull thermostat bracket (5) far enough out to remove two sets of screws (6) and self-locking nuts (7).
Remove thermostat bracket.
(3) Tag and unsolder wire leads from heater cutout (thermostat) switch (1).
(4) Cut heat shrink tubing to approximately three-quarter inch (1.9 cm) long.
(5) Slip heat shrink tubing on ends of wires to be soldered.
(7) Slip heat shrink tubing in place over solder connections and shrink in place. (See paragraph 4-26.)
(8) Secure heater cutout (thermostat) switch (1) to thermostat bracket (5) with two sets of screws (6) and locking
nuts (7).
(9) Secure thermostat bracket (5) to heater support with two sets of screws (2), lock washers (3), and flat washers
(4).
NOTE
FOLLOW-ON MAINTENANCE:
Connect power at power source.
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