TM 5-4520-241-14
Table 4-2. Organizational Maintenance Troubleshooting - Continued
MALFUNCTION
TESTING OR INSPECTION
CORRECTIVE ACTION
4.
HEATER FAILS TO IGNITE, AND RED INDICATOR LIGHT COMES ON.
Step 1.
Check that fuel supply is adequate and external fuel shutoff is open.
Refill fuel supply tank or open valve.
Step 2.
Check for clogged fuel filter. Disconnect power plug to heater. Open access doors, and loosen
knurled nut at bottom of fuel filter. Swing aside the bail and pull off bowl and gasket.
Wipe the inside of the bowl with a clean cloth. Discard and replace the gasket if it is cracked or
torn. Unscrew and remove the filter element and clean by washing in solvent (fed. spec. P-D-
680). If element discs are dented or bent, or cannot be cleaned by washing with solvent, replace
element. Reinstall element, bowl, and gasket, and secure by installing bail. Tighten knurled nut.
Step 3.
Check for fuel input at FUEL RECEPTACLE. Disconnect fuel supply line at heater case, and insert
into can or pail. Connect power plug and turn on heater. If room thermostat is set above ambient
temperature fuel should flow from line.
External fuel pump is not supplied with heater. If there is no fuel flow, check pump and lines per
applicable instructions.
Step 4.
Check for power to external fuel pump. Disconnect fuel pump plug. Connect power plug and turn
on heater. Check for 24 VDC at terminal in EXTERNAL FUEL PUMP RECEPTACLE.
If there is no power, check fuel pump power supply per steps 5 and 6. If there is power, check
fuel pump cable and plug per step 7.
Step 5.
Check wiring to fuel receptacle. Check that yellow wire from fuel pump power supply is tight in
electrical connector. Check that fuel pump power supply is securely fastened to heater case, since
negative side of power supply output is grounded to case. Check wire connections at receptacle,
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