Troubleshooting - Nordyne O4MD Installation, Operation And Maintenance Manual

Appendix C
TROUBLESHOOTING
Problem Possible Cause Remedy
Check thermostat and adjust. Also, check thermostat
Thermostat not calling for
for accuracy; if it is a mercury switch type, it might be off
heat.
level.
Furnace will not start.
No power to furnace.
Thermostat faulty.
Protector relay faulty.
Photo Cell wiring shorted
or room light leaking into
photo cell compartment
Open safety switch.
No fuel oil.
Furnace will not start Clogged nozzle.
without first pushing Clogged oil filter.
protector relay reset
button.
(Happens on frequent Low oil pump pressure.
basis)
Check furnace switch, main electrical panel furnace
fuse or circuit breaker. Also look for any other hand
operated switch, such as an old poorly located furnace
switch that was not removed during furnace
replacement.
Check reset button on protector relay. Remove
thermostat wires from protector relay terminals T1-T2.
Place a jumper across T1-T2. If furnace starts, replace
thermostat, thermostat sub-base (if equipped), or both.
Check reset button on protector relay. Remove
thermostat wires from protector relay terminals T1-T2.
Check for 24v across T1-T2. If no voltage is present,
check for 115v to protector relay. If 115v is present,
replace protector relay.
Check cad cell wiring for short circuits. Also, check for
room light leaking into cad cell compartment. Repair
light leak if necessary.
Check for open limit or auxiliary limit, open door switch
(if equipped). Also, check internal wiring connections;
loose connectors, etc.
Check fuel oil supply. Check that all hand operated fuel
oil valves are in the open position. Fill oil storage tank if
necessary.
Replace nozzle with high quality replacement. Use
rating plate or Tables in Appendix A as a guide.
Replace oil tank filter or in-line filter if used.
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.
Furnace starts, but
cuts out requiring
manually resetting
the oil protector reset
button.
Air getting into fuel oil Check fuel oil lines. Replace any compression fittings
lines, or fuel oil line dirty, found with high quality flared fittings. Check for any
clogged, or in some signs of oil leaks. Any oil leak is a potential source of air
manner defective, or contaminants.
Defective burner motor.
Photo Cell (Cad Cell)
defective.
Check burner motor. If burner motor is cutting out on
over-load, determine why. Replace if necessary.
If cad cell is dirty, clean it. (Determine why cad cell is
getting dirty). If cad cell is poorly aimed, realign it.
NOTE: The cad cell should have a resistance of 100K
_) in absence of light; a maximum of 1500 _) in the
presence of light. Ensure that room light is not leaking
into the cad cell compartment.
25 153B0801