Desa B350D Service Manual

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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 L15TROUBLESHOOTING — PROBLEM CONDITIONSOBSERVED PROBLEMMotor starts, but heater will not ignite.POSSIBLE CAUSEIf No Spark Observed at Spark PlugA. Spark plug has incorrect gapB. Defective transformer or transformer notgrounded properlyC. Cracked spark plugPOSSIBLE CAUSEIf Spark Observed at Spark PlugD. Incorrect fuel pump pressureE. Defective fuel solenoid valveF. Fuel line leak on suction side of pumpG. Dirty or damaged nozzleH. Dirty fuel filterTEST PROCEDURESA. Spark plug has incorrect gap1. Unplug heater.2. Remove upper shell of heater.3. Remove spark plug from burner head.4. Check gap between spark plug electrodeswith feeler gage. Correct gap for sparkplug is .05/.06 inch. Reset gap if needed.5. Follow steps in procedure “B” to test forspark at spark plug electrodes.Figure 19 - Proper Gap betweenSpark Plug Electrodes.05/.06 inch1. 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 pluggap)4. Check to make sure the transformer isproperly grounded by the 2 mountingscrews. Look for loose fasteners, corro-sion, broken tabs, etc.5. Connect the transformer secondary leadto the spark plug.6. Establish a good ground between thespark 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 atspark 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 theground is good and there is no sparkbetween electrodes, the transformer isdefective.Note: No spark between elec-trodes may be caused by cracked porce-lain on the spark plug. Before replacingtransformer, see test procedure “C” onpage 16. If porcelain on spark plug is notcracked, proceed with replacing defec-tive transformer.Figure 20 - Grounding Spark PlugB. Defective transformerGroundingWire!WARNING ICON G 001WARNINGBefore attempting this test procedure,remove fan from motor and disconnectelectrical leads from fuel solenoid valve.This will prevent injury from turning fanor accidental ignition of fuel.!WARNING ICON G 001WARNINGAfter connecting heater to electricalsupply, do not touch spark plug elec-trodes. Spark plug produces high volt-age. Electrical shock will occur.Continued