TM 5-3810-307-24-1-1
Direct/General Support Troubleshooting - Continued
SYMPTOM
PROBABLE CAUSE
CORRECTIVE ACTION
3. Motor runs but there is no
e. Malfunctioning tilt switch.
e. Check that tilt switch is secure
ignition (continued).
in its bracket and in a vertical
position with electrical leads
pointing down. Check leads on
both sides of switch for power.
Replace switch if defective.
f. Excessive fuel flow.
f. Check float level, fuel pressure,
and carburetor fuel needle
setting. Excessive fuel flow will
cause rapid buildup of carbon in
heat exchanger. Correct fuel
feed is 1 oz/3.5 minutes (8
cc/minute).
g. Restricted circulating air
g. Check for restrictions in air
flow.
circulating system.
h. Malfunction in fuel heater
h. Check fuel heater and glow
and glow plug circuits.
plug circuits with START-OFF
switch in START position. If
there is power but no heat from
these parts, replace them. If
there is no power, during
preheating, check all electrical
connections, wires, and
thermostat [opens at 85F
(29C) and closes at 70F
(21C)].
4. Inadequate heat output.
a. Low voltage.
a. Check for 22 vdc minimum
voltage to heater.
b. Carbon buildup.
b. Heat exchanger may have a
heavy coating of carbon
internally. Clean exchanger
and check for excessive fuel
flow, refer to Symptom 3.
c. Incorrect adjustment of HI-
c. Check HI-LO control and
LO control and microswitch.
microswitch adjustment.
5. Fan fails to go to high
a. Malfunctioning relay.
a. Check relay and replace if
speed during burner
defective.
cycle.
b. Malfunctioning motor.
b. With power on, touch orange
motor lead to red motor lead,
fan speed must increase.
Replace motor if defective.
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