H I G H P R E S S U R E P O R T A B L E F O R C E D A I R H E A T E R S E R V I C E M A N U A L
15
TROUBLESHOOTING — PROBLEM CONDITIONS
OBSERVED PROBLEM
Motor starts, but heater will not ignite.
POSSIBLE CAUSE
If No Spark Observed at Spark Plug
A. Spark plug has incorrect gap
B. Defective transformer or transformer not
grounded properly
C. Cracked spark plug
POSSIBLE CAUSE
If Spark Observed at Spark Plug
D. Incorrect fuel pump pressure
E. Defective fuel solenoid valve
F. Fuel line leak on suction side of pump
G. Dirty or damaged nozzle
H. Dirty fuel filter
TEST PROCEDURES
A. Spark plug has incorrect gap
1. Unplug heater.
2. Remove upper shell of heater.
3. Remove spark plug from burner head.
4. Check gap between spark plug electrodes
with feeler gage. Correct gap for spark
plug is .05/.06 inch. Reset gap if needed.
5. Follow steps in procedure “B” to test for
spark at spark plug electrodes.
Figure 19 - Proper Gap between
Spark Plug Electrodes
.05/.06 inch
1. Unplug heater.
2. Remove upper shell of heater.
3. Remove spark plug from burner head.
Make sure spark plug is properly gapped
(see test procedure “A” for spark plug
gap)
4. Check to make sure the transformer is
properly grounded by the 2 mounting
screws. Look for loose fasteners, corro-
sion, broken tabs, etc.
5. Connect the transformer secondary lead
to the spark plug.
6. Establish a good ground between the
spark plug body and heater. To do this,
attach a grounding wire to heater shell.
Clip grounding wire to grounding (outer)
electrode on spark plug (see Figure 20).
Use insulated pliers to hold spark plug at
spark plug hex (see Figure 20).
Note:
Only use pliers with plastic or rubber-
sleeved handles.
7. Connect heater to electrical supply.
8. Look for spark between electrodes. If the
ground is good and there is no spark
between electrodes, the transformer is
defective.
Note: No spark between elec-
trodes may be caused by cracked porce-
lain on the spark plug. Before replacing
transformer, see test procedure “C” on
page 16. If porcelain on spark plug is not
cracked, proceed with replacing defec-
tive transformer.
Figure 20 - Grounding Spark Plug
B. Defective transformer
Grounding
Wire
!
WARNING ICON
G 001
WARNING
Before attempting this test procedure,
remove fan from motor and disconnect
electrical leads from fuel solenoid valve.
This will prevent injury from turning fan
or accidental ignition of fuel.
!
WARNING ICON
G 001
WARNING
After connecting heater to electrical
supply, do not touch spark plug elec-
trodes. Spark plug produces high volt-
age. Electrical shock will occur.
Continued
