TM 5-4520-240-14
Section V. TROUBLESHOOTING
tions. If a malfunction is not listed or is not corrected
4-10. General.
by listed corrective actions, notify your supervisor.
a. This section contains troubleshooting information
c. Only those functions which are solely within the
for locating and correcting most of the operating trou-
scope of organizational maintenance are listed.
bles which may develop in the space heater, Each mal-
function is followed by a list of tests or inspections
4-11.
Organizational Maintenance
which will help you to determine probable causes and
Troubleshooting Chart.
corrective actions to take. Perform the
Refer to table 4-2 for troubleshooting which is allocated
tests/inspections and corrective actions in the order
to organizational maintenance levels.
listed.
NOTE
b. This manual cannot list all malfunctions that may
Before you use this table, be sure you have performed
all applicable operating checks (para 4-3c).
occur, nor all tests or inspections and corrective ac-
Table 4-2. Organizational Maintenance Troubleshooting
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
WARNING
The ignition system of this space heater contains dangerous voltages which can cause severe
electrical shock. Be extremely careful when making voltage measurements or other checks
with the heater connected to the power source during troubleshooting. Always disconnect
the power cable connector before making any continuity tests.
1. HEATER FAILS TO START (NO FLAME, NO BLOWER).
Step 1. Check that fuse is not blown.
Replace blown fuse.
Step 2. Inspect room thermostat wiring for loose connections.
Tighten loose connections or repair broken leads.
Step 3. Turn the ON-OFF switch on. Set thermostat to its highest settings, remove cover, and jump thermostat terminals with an insul-
ated screwdriver.
Replace thermostat if heater starts when jumped.
2. HEATER FAILS TO START (NO HEAT; BLOWER RUNS UNTIL RESET SWITCH TRIPS).
Step 1. Remove fuel strainer filter element and check for clogging.
Service fuel strainer (para 4-21a).
Step 2. Check that fuel pump filter is not clogged.
Service fuel pump filter (para 4-22a).
Step 3. Check that power is available to fuel pump and fuel solenoid (fig. 1-4.
If no power is available, check electrical connections.
Step 4. Disconnect fuel tube at float bowl inlet and turn power on.
Replace fuel pump if power is available but no fuel flows from fuel tube.
Step 5. Remove the igniter and check for damage (para 4-30).
Replace a damaged igniter.
Step 6. Remove glow plug and ground it against unpainted surface of burner. Attempt to start heater.
Replace glow plug if it fails to heat (para 4-30).
Step 7. Remove fuel adjustment needle. Turn power on, and check that fuel flows from opening.
Replace solenoid coil if no fuel flows (para 4-23).
3. HEATER IGNITES BUT BLOWER FAILS TO RUN.
Check that motor brushes are not worn, burned, or damaged.
Replace brushes if brush lead is broken, or if brushes are burned or worn to less than 5/16 inch (para 4-27).
4. HEATER OVERHEATS, CYCLING UNDER CONTROL OF OVERHEAT THERMOSTAT.
Step 1. Check for restricted air flow.
Remove any obstacles restricting air flow.
Step 2. Check motor for worn or damaged brushes that could cause slow motor and fan speed.
Replace brushes if a brush lead is broken, or if brushes are burned or are worn to less than 5/16 inch (para 4-27).
5. HEATER BACKFIRES.
Step 1. Check that fuel adjustment is correct.
Adjust fuel adjustment needle (para 4-23a).
4-5
