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650.75-N4U
be caused by a gas valve that leaks through or is slow clos-
ing.
2 FLASH:This indicates that the normally open pressure
switch contacts are stuck in the closed position. The control
confirms these contacts are open at the beginning of each
heat cycle. This would indicate a faulty pressure switch or
mis-wiring.
3 FLASH:This indicates the normally open pressure switch
contact did not close at the beginning of the heat cycle. This
could be caused by a number of problems; faulty inducer,
blocked vent pipe, high winds at vent terminal, broken pres-
sure switch hose or faulty pressure switch.
4 FLASH:This indicates the auxiliary limit switch has opened
its normally closed contacts. With this fault code the control
will operate the supply air blower and inducer. This condition
may be caused by: dirty filter, improperly sized duct system,
incorrect blower speed setting, incorrect firing rate or faulty
blower motor.
5 FLASH:This fault is indicated if the normally closed con-
tacts in the rollout switch opens. The rollout control is manu-
ally reset. If it has opened, check for proper combustion air,
proper inducer operation, primary heat exchanger failure or
burner problem. Be sure to reset the switch after correcting
the failure condition.
6 FLASH:This indicates that after the unit was operating, the
pressure switch opened 5 times during the call for heat. This
could be caused by a number of problems; blocked vent or
combustion air intake, high winds at vent terminal, faulty
inducer, cracked pressure switch hose, or a blockage in the
condensate drainage system.
7 FLASH:This fault code indicates that flame could not be
established. This no-light condition occurred 3 times during
the call for heat before locking out. This may be caused by
low gas pressure, faulty gas valve, faulty hot surface igniter
or burner problem.
8 FLASH:This fault is indicated if the flame is lost 5 times
during the heating cycle. This could be caused by low gas
pressure or faulty gas valve.
LED ON CONSTANTLY:This indicated an internal fault in the
furnace control discovered during its self-check procedure.
Replace the control.
60 MINUTE AUTOMATIC RESET FROM LOCKOUT:This
control includes a watchdog type circuit that will reset from a
lockout condition after 60 minutes. Operational faults 6, 7 & 8
will be reset. This provides protection to an unoccupied struc-
ture if a temporary conditions exists causing a unit malfunc-
tion. An example would be a low incoming gas supply
pressure condition preventing unit operation. When the gas
pressure was restored, at some point the watchdog would
restart the unit and provide heat for the house.
38
NOTE:The control will blink one time when initially powered.
This is normal and not an indication of any malfunction.
RESET FROM LOCKOUT:To reset the control from any lock-
out condition break the line voltage supply or 24 volt signal
from the thermostat for 30 seconds.
Do not try to repair controls. Replace defective
controls with Source 1 Parts.
Never adjust pressure switch to allow furnace
operation.
Never jump pressure switch or rewire in an
attempt to allow furnace operation. To do so will
allow furnace to operate under potentially hazard-
ous conditions.
035-14370-000
Unitary Products Group
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