TM 5-4520-241-14
SECTION XII. MAINTENANCE OF ACCESSORY ITEMS
4-42.
DESCRIPTION.
a. Room Thermostat. The room thermostat is mounted remote from the heater, but controls heater operation. It
energizes or deenergizes the heater after sensing ambient temperature and comparing it with the thermostat setting. A
differential of approximately 2F is built in so that the heater will not cycle constantly.
b. Side Covers. The two side heater case covers are shipped separately although their mounting hardware is on the
heater assembly. The side covers are only used when air intake is through the bottom rather than through the louvers, or
when the heater is stored.
4-43.
ROOM THERMOSTAT.
WARNING
This space heater contains dangerous voltages which can cause severe electrical
shock. Be sure to disconnect the power plug before repairing the heater.
a. Testing.
(1) Turn off the heater. Disconnect the thermostat cable from the ROOM THERMO receptacle on the side of the
heater control box.
(2) Loosen the screw at the bottom of the room thermostat cover, and pull off the cover for access to the switch
inside.
(3) Slowly rotate the knob back and forth. You should be able to detect a distinct click as the dial is rotated past
the ambient temperature, as long as the ambient temperature is within the thermostat range.
(4) If you cannot detect a click, use a self-powered test light or an ohmmeter to check continuity across the switch
terminals as you rotate the knob. There should be no continuity when the thermostat is set above ambient temperature by
2 or more, and continuity when it is set below ambient temperature by 2 or more.
b. Replacement . No repair of the thermostat is possible. If it does not operate as described above, replace as
follows:
(1) Disconnect the thermostat cable from the ROOM THERMO receptacle on the side of the heater control box.
(2) Loosen the screw at the bottom of the thermostat cover, and pull off the cover for access to the wire
connections.
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