SM14-001-0
Page 13
SYMPTOM
PROBABLE CAUSE
SOLUTION
3. Motor runs
but there is no
g.
Restricted circulating air flow.
g. Check for restrictions in the air
-
circulating system, which could
cause overheating.
(continued)
h. Malfunction in the fuel heater
h. Check the fuel heater and glow
plug circuits with the START-OFF
and glow plug circuits.
switch to START. If there is power
but no heat from these parts,
replace the faulty component. If
there is no power to the fuel heater
during preheating. check all con-
nections, wires, and the thermostat
which opens at 85 degrees F (29
degrees C) and closes at 70 degrees
F (21 degrees C).
4.
Inadequate heat output.
a. Check for low voltage. The
a.
Low voltage.
heater must have 21 volts min-
imum so that the motor turns fast
enough to ensure adequate com-
bustion air flow.
b.
Carbon buildup.
b. The heat exchanger may have
a heavy coating of carbon inter-
nally. Check fuel flow as described
under, Motor runs - but there is no
c. Incorrect adjustment of HI-LO
c. Check Hi-LO control and mi-
microswitch and bi-metal blade.
croswitch adjustment. Refer to ad-
justment and repair. HI-LO control
and microswitch.
5. Fan fails to go to high speed
a.
Malfunctioning relay.
a. Check the relay. Replace if
defective.
during burning cycle.
b.
Malfunctioning motor.
b. Check motor and connections.
With the power on, touch the
orange motor lead to the red motor
lead; speed must increase. Replace
the motor if defective.
c. Loose or broken electrical
c. Check electrical connections.
Repair or replace if necessary.
connections.
d. Malfunctioning HI-LO control
d. Check HI-LO control and mi-
and microswitch.
croswitch adjustment. Refer to Ad-
justment and Repair. HI-LO Control
and Microswitch.
