TM 5-4520-241-14
(6) Open the control box, and unlock the two studs which secure the control box to the heater case. Rotate the
control box so that the printing on the control box cover is upright, and tighten the two studs. Close the control box.
e. Side Covers. The side covers, which are packed separately, may be used to cover the louvers when they are not
needed as air inlets. Remove the four screws from the heater side panel, install the cover, and replace the screws.
4-5.
INITIAL CHECKOUT AND ADJUSTMENT.
After installation, check heater operation as follows:
a. Move the HEATER-OFF-FAN switch to FAN. The white indicator should not light and the ventilating blower
motor must start immediately to expel air from the heater. Check for air flow, and ensure that there are no obstructions in
the path of the discharged air.
b. Set the thermostat knob to less than ambient temperature. Move the HEATER-OFF-FAN switch to HEATER.
The ventilating blower must stop, the white indicator light must be on, and the red indicator light must be off.
c. Start heater operation by setting the thermostat knob to a temperature above ambient temperature. The
combustion motor should start immediately, but not the ventilating motor so that there is no air flow in the enclosure. The
external fuel pump should start simultaneously, and there may be a slight buzzing or hissing from the ignition system.
d. Unless the ambient temperature is extremely low, the heater should ignite within a minute, as evidenced by
the starting of the ventilating motor. At low ambient temperatures when diesel fuel or fuel oil is used; the burner may not
ignite within the time allowed by the time delay assembly, and the red indicator will light. If this occurs, wait a few minutes
then push the RESET button on the control box. Open the front access door and pull out the choke knob on the
carburetor. Hold it out until ignition occurs and you can hear combustion in the burner.
e. After allowing a few minutes for the heater to warm up, check the exhaust for smoke, and check for erratic
operation. If either condition occurs, adjust the fuel needle as follows:
NOTE
Adjustment can be made directly through the front access door. There is no need
to remove any panels.
(1) Turn the fuel needle (fig. 4-3) clockwise gently until it is seated in the carburetor body.
4-6 Change 2
