20
Table C-3: System and General Troubleshooting
continued
Problem Possible
Cause
Remedy
Photo Cell wiring shorted or
room light leaking into photo
cell compartment
Check photo cell (cad cell) wiring for short circuits. Also, check for
room light leaking into cad cell compartment. Repair light leak if
necessary. See Table C-2.
Furnace will not start.
Open safety switch.
Check for open limit or auxiliary limit. Also, check internal wiring
connections; loose connectors, etc.
No fuel oil.
Check fuel oil supply. Check that all hand operated fuel oil valves
are in the open position. Fill oil storage tank if necessary.
Clogged nozzle.
Replace nozzle with high quality replacement. Use rating plate or
Tables in Appendix A as a guide.
Clogged oil filter.
Replace oil tank filter or in-line filter if used.
Low oil pump pressure.
Connect pressure gauge to oil pump. Adjust pump pressure, or
replace oil pump if necessary. Ensure that erratic pressure
readings are not caused by defective fuel oil line.
Air getting into fuel oil lines, or
fuel oil line dirty, clogged, or in
some manner defective.
Check fuel oil lines. Replace any compression fittings found with
high quality flared fittings. Check for any signs of oil leaks. Any oil
leak is a potential source of air or contaminants.
Furnace will not start
without first pushing
oil primary control
reset button.
(Happens on frequent
basis)
Defective burner motor.
Check burner motor. If burner motor is cutting out on over-load,
determine why. Replace if necessary.
Furnace starts, but
cuts out requiring
manually resetting the
oil protector reset
button.
Photo Cell (Cad Cell) defective.
If cad cell is dirty, clean it. (Determine why cad cell is getting dirty).
If cad cell is poorly aimed, realign it. NOTE: The photocell should
have a resistance of 100K
Ω
in absence of light; a maximum of
1500
Ω
in the presence of light. Ensure that room light is not
leaking into the cad cell compartment. (see diagnostic light
section, or manually measure cad cell resistance).
No fuel oil.
Check fuel oil supply. Check that all hand operated fuel oil valves
are in the open position. Fill oil storage tank if necessary.
Clogged nozzle.
Replace nozzle with high quality replacement. Use rating plate or
Tables in Appendix A as a guide.
Clogged oil filter.
Replace oil tank filter or in-line filter if used.
Low oil pump pressure.
Connect pressure gauge to oil pump. Adjust pump pressure, or
replace oil pump if necessary. Ensure that erratic pressure
readings are not caused by defective fuel oil line.
Air getting into fuel oil lines, or
fuel oil line dirty, clogged, or in
some manner defective.
Check fuel oil lines. Replace any compression fittings found with
high quality flared fittings. Check for any signs of oil leaks. Any oil
leak is a potential source of air or contaminants.
Defective burner motor.
Check burner motor. If burner motor is cutting out on over-load,
determine why. Replace if necessary.
Water or contaminants in oil.
Drain fuel oil storage tank; replace fuel oil. (Consult with fuel oil
supplier).
Furnace starts, but
cuts out requiring
manually resetting the
oil protector reset
button.
Frozen oil line.
Gently warm oil line. Insulate oil line. (Outdoor piping size may
require increased diameter).
Electrodes out of adjustment or
defective.
Check electrode settings. Check electrodes for dirt build-up or
cracks in porcelain.
Poor transformer high voltage
connections or defective
transformer.
Check contacts between the igniter and electrodes. If OK, replace
the igniter
Fuel oil filter clogged.
Replace fuel oil storage tank filter and / or fuel oil in-line filter.
Defective oil pump.
Check burner motor / fuel oil pump coupling. Check oil pump
pressure. Replace fuel oil pump if necessary.
Oil burner sputtering
at nozzle
Fuel oil line partially clogged or
contains air.
Bleed air from oil line. If problem persists, replace oil line.
Continues on next page
