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PROBLEM 6: BURNERS LIGHT WITH HEATING DEMAND BUT UNIT SHUTS DOWN
PREMATURELY (CONT.)
6.5
- Combustion air blower energizes
with a heating demand.
- Burners light.
- Diagnostic lights flash watch guard
flame failure.
- NOTE" Unit might go into 60 minĆ
ute Watchguard mode depending on
intermittent nature of sensor signal.
LED#1-Alternating Slow Flash
LED#2-Alternating Slow Flash
6.5.1
Loose sensor wire connection
causes intermittent loss of flame sigĆ
nal.
ACTION 1 - Check that the sensor is properly loĆ
cated.
ACTION 2 - Check that the sense wire is properĆ
ly attached to both the sensor and the control.
Pay extra attention to the pin connectors.
PROBLEM 7: CONTROL SIGNALS LOW FLAME SENSE DURING HEATING MODE
Condition Possible Cause Corrective Action/Comments
7.0
- Unit operates correctly but the
diagnostic lights flash low flame
7.1.1
Sense rod is improperly located on
the burner.
ACTION 1 - Check the sense rod for proper locaĆ
tion on the burner. Properly locate the sense rod
or replace if rod cannot be located correctly.
.
LED#1-Slow Flash
LED#2-Fast Flash
7.1.2
Sense rod is contaminated.
ACTION 1 - Check sense rod for contamination
or coated surface. Clean the sense rod with steel
wool or replace sensor. DO NOT USE SAND PAĆ
PER TO CLEAN ROD. SAND PAPER WILL
CONTRIBUTE TO THE CONTAMINATION
PROBLEM.
PROBLEM 8: INDOOR BLOWER FAILS TO OPERATE IN COOLING, HEATING, OR CONTINUOUS
FAN MODE
Condition Possible Cause Corrective Action/Comments
8.0
- Indoor blower fails to operate in
continuous fan, cooling, or heating
mode.
8.1.1
Miswiring of furnace or improper conĆ
nections at control or indoor blower
motor.
ACTION 1- Correct wiring and/or replace any
loose connections. Check for correct wiring and
loose connections.
8.1.2
120V is not being supplied to the inĆ
door air blower or blower motor failĆ
ure.
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 moĆ
tor tap but the blower does not operate, replace
the motor.
8.1.3
Defective control board
ACTION 1 - If there is not 120V when "Y", "G", or
"W" is energized, replace the control.
PROBLEM 9: RF STATIC DURING TIME FOR IGNITION
Condition Possible Cause Corrective Action/Comments
-AM radio interference Ignitor operation
ACTION 1- Call Technical Support, Dallas
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