Troubleshooting; Table C-2: Cad Cell Resistance - Nordyne O4HD-091A-12-FA Installation Instructions Manual

R7184 LED DIAGNOSTIC LIGHT
The LED diagnostic light has several
functions. It indicates the state or mode
in which the oil burner is operating. It will
also indicate fault conditions, and help
determine cad cell resistance while the
burner is operating.
NORMAL CONDITIONS:
The LED diagnostic light will turn on
when the burner enters the carryover
state; the point at which ignition spark is
on, and will remain on through the run
state, where the ignition
terminated but the burner continues to
fire.
The LED diagnostic light will turn off at
the end of the burner cycle as the R7184
enters the idle state, and will remain off
until the next heating cycle.
FAULT CONDITIONS:
If the LED diagnostic light is flashing
quickly; 1 Hz (½ second on / ½ second
off), the R7184 is in the lockout state or
in restricted mode. To exit the lockout
state, press the reset button.
If the LED diagnostic light is flashing
slowly; ¼ Hz (2 seconds on / 2 seconds
off), the R7184 is in the recycle state.
This indicates that flame sensing was
lost after the lockout timer expired during
the ignition carryover state. The R7184
will return to the idle state within 60
seconds.
CAD CELL CONDITION:
If the LED diagnostic light is off, the cad
cell is not sensing flame.
If the LED diagnostic light is on, the cad
cell is sensing flame, or viewing ambient
light.
The resistance of the cad cell may be
checked while the R7184 is in the run
state by pressing the reset button. The
LED diagnostic light will flash the
following code:
Flashes Resistance in Ohms
1 Less than 400
2 Between 400 - 800
3 Between 800 – 1600
4 Between 1600 - 5000

Table C-2: Cad Cell Resistance

Troubleshooting

IMPORTANT:
Due to the potential hazard of line
voltage, only a trained, experienced
service technician should perform the
troubleshooting procedure.
PRELIMINARY STEPS:
Check the diagnostic light for indications
of burner condition. Refer to R7184 LED
DIAGNOSTIC LIGHT
When simulating a call for heat at the
R7184, disconnect
thermostat lead wire from the T1 - T2
terminals to prevent damage to the
spark is
thermostat. Neglecting this procedure
may burn out the heat anticipator of a
standard 24
harm to components within a micro-
electronic thermostat.
Before checking the oil primary control,
perform these preliminary checks, (repair
or replace controls as necessary):
• Check the power supply; fuse box or
breaker, any service switches, all
wiring connections, and burner motor
reset button (if equipped).
• Check the limit switches to ensure that
the switch contacts are closed.
• Check the electrode gap and position.
• Check the contacts between the oil
primary control and the electrodes.
• Check oil supply (tank gauge).
• Check the oil nozzle, oil filter, and oil
valves.
• Check the piping or tubing to the oil
tank.
• Check the oil pump pressure.
CHECK OIL PRIMARY CONTROL AND
IGNITOR
If the trouble does not appear to be in
the burner or ignition hardware, check
the oil primary control and the ignitor by
using the following equipment:
Screwdriver.
Voltmeter (0 - 150
Insulated jumper wires with both ends
stripped.
ELECTRICAL SHOCK HAZARD.
Troubleshooting is done with the system
powered. Be careful to observe all
necessary
electrical shock or equipment damage.
section for details.
at least one
thermostat, or cause
VAC
)
VAC
precautions to prevent
22
PRELIMINARY CHECKS:
Make sure that limit switches are closed
and that contacts are clean.
Check for line voltage power on the oil
primary control black and white lead
wires.
Refer to Table C-3 or C-4 for further
troubleshooting information.
151B0801 R5 3/28/2006