York G8C, GF8 service manual 035-19992-001Rev. A, Unitary Products Group

035-19992-001 Rev. A (0404)

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

Unitary Products Group 9