Lennox G50UHi Unit Information page 33

PROBLEM 6: BURNERS LIGHT WITH HEATING DEMAND BUT UNIT SHUTS DOWN
6.5
− Combustion air inducer energizes
with a heating demand.
− Burners light.
− Diagnostic lights flash watch guard
flame failure.
− NOTE" Unit might go into 60 minute g g
Watchguard mode depending on in- W t h d d d di
termittent nature of sensor signal.
LED#1−Alternating Slow Flash
LED#2−Alternating Slow Flash
PROBLEM 7: CONTROL SIGNALS LOW FLAME SENSE DURING HEATING MODE
Condition
7.0
− Unit operates correctly but the diag-
nostic lights flash low flame sense
code code.
LED#1−Slow Flash
LED#2−Fast Flash
PROBLEM 8: INDOOR BLOWER FAILS TO OPERATE IN COOLING, HEATING, OR CONTINUOUS
Condition
8.0
− Indoor blower fails to operate in
continuous fan, cooling, or heating
mode.
Condition
9.0
− AM radio interference.
PREMATURELY (CONT.)
Loose sensor wire connection causes
intermittent loss of flame signal.
i
Poor ground to burner box
Possible Cause
Sense rod is improperly located on
Sense rod is contaminated.
Possible Cause
Miswiring of furnace or improper con-
nections at control or indoor blower
120V is not being supplied to the
indoor air blower or blower motor fail-
Defective control board
Defective run capacitor
PROBLEM 9: RF STATIC DURING TIME FOR IGNITION
Possible Cause
Ignitor operation
6.5.1
6.5.2
7.1.1
the burner.
7.1.2
FAN MODE
8.1.1
motor.
8.1.2
ure.
8.1.3
8.1.4
9.1.2
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ACTION 1 − Check that the sensor is properly lo-
cated.
ACTION 2 − Check that the sense wire is properly
attached to both the sensor and the control. Pay
extra attention to the pin connectors.
ACTION 1 − Check for proper ground and repair
as necessary.
Corrective Action/Comments
ACTION 1 − Check the sense rod for proper loca-
tion on the burner. Properly locate the sense rod
or replace if rod cannot be located correctly.
ACTION 1 − Check sense rod for contamination
or coated surface. Clean the sense rod with steel
wool or replace sensor. DO NOT USE SAND PA-
PER TO CLEAN ROD. SAND PAPER WILL
CONTRIBUTE TO THE CONTAMINATION
PROBLEM.
Corrective Action/Comments
ACTION 1− Correct wiring and/or replace any
loose connections. Check for correct wiring and
loose connections.
ACTION 1 − Check for 120V at the various calls
for indoor blower by energizing "Y", "G", and "W"
individually on the low voltage terminal strip. Note
that when "W' is energized, the blower is delayed
45 seconds. If there is 120V to each motor tap but
the blower does not operate, replace the motor.
ACTION 1 − If there is not 120V when "Y", "G", or
"W" is energized, replace the control.
ACTION 1 − Replace capacitor
Corrective Action/Comments
ACTION 1 − Call Technical Support, Dallas.