(4) The thermal cutout switch (S4) protects the combustion motor from thermal overload. It opens at 223°F
(106°C) to deenergize the motor, and closes at 144°F (62°C) to reestablish combustion air flow.
This space heater contains dangerous voltages which can cause severe electrical
shock. Be sure to disconnect the power plug before repairing the heater.
(1) Disconnect the power plug from the power receptacle.
(2) The wiring harness is not repairable at the organizational level. To remove it for replacement with a new
harness, remove one of the two louver panels. Also remove the control box from the heater case by turning the two studs
counterclockwise. Unplug the wiring harness.
(3) Remove nuts (1), (1, fig. 4-26), lock washers (2), and screws (3) to remove the female receptacle (4) from the
heater case. Leave all wires attached.
(4) If filter and receptacle assembly (8) must be replaced, remove screws (5), lock washers (6), and dust cap and
chain (7) and remove the assembly from the heater case. Disassemble the receptacle and unsolder the wires.
(5) If fuel pump receptacle (13) must be replaced, remove nuts (9), washers (10), dust cap and chain (11), and
screws (12), and remove the receptacle from the heater case. Disassemble the receptacle and unsolder the wires.
(6) Disconnect the ten wires from their connecting points as indicated in the wiring diagram inside the right side
access door. Tag all leads to aid in reassembly. Carefully pull the wires through the grommet in the heater case one at a
time, to avoid damaging the terminals or breaking the wire/terminal board.
b. Replacement . Install in the reverse order of removal. Be sure that all wires are securely fastened to their
respective terminals. Spray soldered joints with a moisture repellent conforming to MIL-V-173 (Columbia Technical Humi-
Seal, No. 1A27, Class A, or equivalent).