035-17480-000 Rev. A (800)
Unitary Products Group
31
All flash code sequences are broken by a 2 second off period.
CONTINUOUS FLASHING (1 sec on - 1 sec off): This indi-
cates that flame was sensed when there was not a call for
heat. With this fault code the control will also turn on both the
inducer motor and supply air blower. This fault would typically
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 that a primary limit, or auxiliary limit,
or rollout limit switch has opened its normally closed contacts.
With this fault code the control will operate the supply air
blower and the ventor. This condition may be caused by: dirty
filter, improperly sized duct system, incorrect blower speed
setting, incorrect firing rate or faulty blower motor. The rollout
control is manually 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 4 times during the call for heat. This
could be caused by a number of problems; blocked vent or
chimney, faulty inducer, cracked pressure switch hose.
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,
reversed line polarity, 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 indicates 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. This provides protection to
an unoccupied structure if a temporary conditions exists
causing a unit malfunction. An example would be a low
incoming gas supply pressure condition preventing unit oper-
ation. When the gas pressure was restored, at some point the
watchdog would restart the unit and provide heat for the
house.
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
lockout condition break the line voltage supply or 24 volt sig-
nal from the thermostat for 30 seconds.
50A51-243 IGNITION CONTROL (P/N 031-01290-000)
Normal flame sense current is approximately
2.4 microamps DC (
µ
a)
Low flame signal control lockout point is
0.15 microamps (DC (
µ
a)
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.
