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035-19992-001 Rev. A (0404)
Unitary Products Group 9
6 FLASH: This indicates that after the unit was operating, the pressure
switch opened 4 times during the call for heat. If the main blower is in a
"Delay on" mode it will complete it, and any subsequent delay off
period. The induced draft motor continues to operate until the pressure
switch re-closes or a call for heat is removed.
7 FLASH: This fault code indicates that the flame could not be estab-
lished. This no-light condition occurred 3 times (2 retries) during the call
for heat before locking out.
CAUSE: This may be caused by low gas pressure, faulty gas
valve, faulty hot surface ignitor or burner problem.
8 FLASH: This fault is indicated if the flame is lost 5 times (5 recycles)
during the heating cycle.
CAUSE: This could be caused by low gas pressure or faulty gas
valve.
9 FLASH: Indicates reversed line voltage polarity. Both heating and
cooling operations will be affected. Check polarity at furnace and
branch.
11 FLASH: This fault will be indicated if the rollout jumper wire connec-
tion soldered into the board is broken. If this fault occurs the control will
have to be replaced.
STEADY ON: This fault occurs if the gas valve is energized when there
is no call for heat. If this happens the induced draft motor is energized
and will remain energized for 5 seconds or until the fault clears itself at
which point the induced draft motor de-energizes.
CAUSE: This failure is counted as a recycle. Check the gas valve
and control for proper operation.
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 1,6,7,8 and Steady On will be reset.
This provides protection to an unoccupied structure if a temporary con-
dition exists causing a furnace malfunction. An example would be a low
incoming gas supply pressure preventing unit operation. When the gas
pressure is restored, at some point the "watchdog" would restart the
unit and provide heat for the house.
IGNITION CONTROL
Normal flame sense current is approximately
3.7 microamps DC (µa)
Low flame signal control lockout point is
0.9 microamps DC (µa)
FIGURE 14: Furnace Control Event Schedule