111907-01AFor more information, visit www.desatech.comFor more information, visit www.desatech.com28TROUBLESHOOTINGThe two most common causes of a malfunctioning gas appliance are:1. Loose wiring connections2. Construction debris clogging the pilot and/or gas control valve filterOBSERVED PROBLEMIgnitor will not spark or pilot will not lightPilot will not stay litNo gas to burner, although wall switch andvalve are set to the ON positionFrequent pilot outagePOSSIBLE CAUSE1. No gas supply, or shutoff valve is OFF2. Air in gas line3. Construction debris clogging pilot orifice4. Low gas pressure5. Kinked pilot line6. Control valve knob is not opening7. No power to unit or the ignition moduleor power transformer is bad8. Vent damper not fully open1. Loose wiring on ignitor wire to ignitionmodule and/or poor ground to ignitionmodule2. Pilot flame too low to sense1. Wall switch wires defective or too long1. Pilot flame may be too low, causingsafety pilot to “drop out”2. Improper venting or excessive blockageREMEDY1. Check to see if you have gas supply andthat equipment shutoff valve is opened2. Repeat lighting procedure several timesto purge all air out of lines. If after re-peated attempts appliance does not light,call for qualified service and repair.3. Remove debris and dirt, inspect andclean any other possible obstructions4. Contact your gas supplier to checkpressure5. Have a qualified technician replace pi-lot line6. Replace control valve (Refer to Replace-ment Parts, page 34)7. Check that main power is on and that allwire connections are made correctly tothe ignition model (see Wiring Diagram,page 24). Check for 24 VAC at the sec-ondary side of the transformer. If 24VAC is present, and the module does notoporate, have the module replaced oth-erwise have the transformer replaced.8. Open vent damper until fully locked inOPEN position1. Check wiring connection. Refer to wir-ing diagram (see Wiring Diagram, page24) and/or check ground wire to igni-tion module2. Clean and adjust pilot burner and checkgas supply and inlet pressure to unitNote: Have a qualified technician replacepilot assembly if broken or corroded1. Check electrical connections1. Clean and adjust pilot flame for maximumflame impingement on thermopile2. Have the vent system inspected, includ-ing the termination cap. Remove anyrestriction or obstructionNote: For additional help, visit DESA’stechnical service web site atwww.desatech.com.Note: Before troubleshooting the system,make sure the gas shutoff valve is ON.TROUBLESHOOTINGWARNING: Turn off heaterand let cool before servicing. Onlya qualified service person shouldservice and repair heater.CAUTION: Never use a wire,needle, or similar object toclean pilot. This can damagepilot unit.