Lennox O23V Series Installation Instructions Manual page 22

Troubleshooting: Burner starts and fires, but short cycles (too little heat)
Source Procedure
Limit Control Connect voltmeter between
line voltage connections to
primary control (black &
white leads). If burner
cycles due to power
interruption, it is cycling on
limit.
Power If voltage fluctuates, fault is
in the power source.
Recheck voltage at the
power source.
Troubleshooting: Burner starts and fires, but loses flame and lock out on safety
Source Procedure
Poor Fire After burner fires,
immediately jumper
across flame detector
terminals at the primary
control.
S
If burner continues to
run (does not lock out
of safety), fault may be
poor fire. Inspect fire.
S
Flame Detector
If fire is good, check for
fault in flame detector
circuit.
S
Oil Supply
If burner loses flame
(does not lock out on
safety), fault is in the
fuel system.
Listen for pump whine
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Causes
Dirty furnace air filters
Blower running too slow
Blower motor seized or burned out
Blower bearings seized
Blower wheel dirty
Blower wheel in backward
Wrong motor rotation
Restrictions in return or supply air
system
Adjustable limit control set too low
Loose wiring connection
Low or fluctuating line voltage
Causes
Unbalanced fire
Too much air − − lean short fire
Too little air − − long dirty fire
Excessive draft
Too little draft or restriction
Dirty CAD cell face
Faulty CAD cell − − exceeds 15000
hms
Loose or defective cad cell wires
Pump loses prime − air slug
Pump loses prime − air leak in
supply line
Water slug in line
Partially plugged nozzle or nozzle
strainer
Restriction in oil line
Plugged fuel pump strainer
Cold oil − outdoor tank
search engine
Correction
Clean or replace filter.
Increase blower speed to maintain proper
temp. rise.
Check for high static pressure.
Check HEAT selector pin per wiring
diagram (figure 18, page 16).
Replace motor.
Replace bearings and shaft.
Clean blower wheel.
Reverse blower wheel.
Replace with properly rotating wheel.
Correct cause of restriction.
Reset limit to maximum stop setting.
Locate and secure connection.
Call power company.
Correction
Replace nozzle
Reduce combustion air − check combustion.
Increase combustion air − check combustion.
Adjust barometric damper for correct draft.
Correct draft or remove restriction.
Clean CAD cell face.
Replace CAD cell.
Secure connections or replace cad cell holder
and wire leads.
Prime pump at bleed port
Check supply line for loose connections and
tighten fittings.
Check oil tank for water (over 1 inch) pump or
drain out water.
Replace nozzle.
Clear restriction.
Clean strainer or replace pump.
Change to number 1 oil.
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