TM 5-4520-241-14
Table 4-2. Organizational Maintenance Troubleshooting - Continued
MALFUNCTION
TESTING OR INSPECTION
CORRECTIVE ACTION
4 - Continued
and green ground connection from receptacle to beater case.
Tighten loose connections. Replace defective terminals or broken wire.
Step 6.
Check power supply output. Turn on heater and check for 24 VDC from yellow wire to heater case
ground.
If output voltage is not present, replace fuel pump power supply. Turn off heater and disconnect
power plug. Disconnect wires from fuel pump power supply to terminal strip, overheat
thermostat, and electrical connector. Remove screws and washers securing fuel pump power
supply to heater case. Remove defective power supply, and install new one by reversing removal
process.
Step 7.
If 24 VDC is available at EXTERNAL FUEL PUMP RECEPTACLE per step 3., check wiring to
external fuel pump. Disconnect fuel pump cable at heater and fuel pump. Check for continuity
using test light or ohmmeter.
If cable is open, disassemble plug and tighten loose connections.
Repair or replace broken
cable.
Step 8.
Check for defective fuel pump. Fuel pump is not supplied with heater.
Repair or replace per applicable instructions.
Step 9.
If fuel system is good, inspect igniter. Open access doors and disconnect ignition cable from
igniter. Remove igniter from burner head and inspect for dirty or damaged electrode.
If igniter is damaged, discard and install a new igniter in the burner head. If fuel deposits are
clogging tip between igniter electrode and ground tube, clean with a wire brush, then reinstall.
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