York International DFAA User's Information, Maintenance And Service Manual page 10

107273-UUM-C-0306
TABLE 4: Cad Cell Resistance When Sensing Flame
Flashes
1 Less than 400
2 More than 400 and less than 800
3 More than 800 and less than 1600
4 More than 1600 and less than 5000
Led
On
Led
Off
FIGURE 12: Example of 800 to 1600 Ohm Cad Cell Resistance
Reading (3 Flashes)
Preliminary Steps
1. Check wiring connections and power supply.
2. Make sure power is on to controls.
3. Make sure limit control is closed.
4. Check contacts between igniter and the electrodes.
5. Check the oil pump pressure.
6. Check the piping to the oil tank.
7. Check the oil nozzle, oil supply and oil filter.
10
Cad Cell Resistance in Ohms
Resetting from Restricted Lockout
If the control locks out three times in a row, without a complete heat
cycle between attempts, the lockout becomes restricted in order to pre-
vent repetitious resetting by the homeowner. To reset, hold down the
reset button for 30 seconds (until the LED flashes).
DIAGNOSTIC INDICATOR KEY
LED
On
Off
Flashing (1/2 sec. on, 1/2 sec. off)
Flashing (2 sec. on, 2 sec. off)
Check Oil Primary Control
If the trouble is not in the burner or ignition hardware, check the oil pri-
mary control by using the following equipment:
1. Screwdriver
2. Voltmeter (0 to 150 VAC range)
3. Insulated jumper wire with both ends stripped.
4. Follow the oil burner operation and oil burner control troubleshoot-
ing steps in Tables 5 and 6.
Electrical Shock Hazard. Can cause severe injury, death, or
property damage. Observe all precautions to prevent electrical
shock or equipment damage. After troubleshooting the system,
follow the procedure "To Turn off Appliance before Servicing.
STATUS
Flame sensed
Flame not sensed
Lockout / Restricted lockout
Recycle
Unitary Products Group