A227_F: Internal Fault: Gas Vlv Rly 2 Welded Shut
Status
This is a critical fault and should rarely (if ever) be seen in the field.
Description
The high gas valve relay on a 2-stage board is welded shut causing gas valve to be energized when it should not.
Expected Operation
If the relay is welded shut and the alarm is active, the unit will respond as follows:
1. Gas valve and igniter will be turned off (if not already turned off).
2. Inducer will immediately be energized at high speed (if not already at high speed).
3. Indoor blower (IBM) will energize at the high heat speed unless there is another call also present – in which case the higher speed shall be used.
4. "A227_F Internal Fault: Gas Vlv 2 Rly Welded Shut", "A126_F Flame not Sensed with Gas Valve On - UL" and "A093_F Internal Control Fault Detected" alarms will be logged.
These states will remain as described above until the condition is gone.
Once this condition is no longer present, the furnace will clear alarm "A227_F Internal Fault: Gas Vlv 2 Rly Welded Shut" and "A093_F Internal Control Fault Detected", complete inducer post-purge and the user set heat blower off delay. The control then proceeds to a one-hour “soft” lockout with the alarm "A115_F One-hour Lockout: Gas Valve Stuck Closed" declared throughout the duration. Upon completion of the lockout, control will clear alarm "A115_F One-hour Lockout: Gas Valve Stuck Closed". Alarm "A126_F Flame not Sensed with Gas Valve On - UL" will remain logged until power is cycled to the unit or a clear alarms command is used to clear the fault. The furnace shall then resume normal operation.
Cause
Faulty furnace control - relay shut closed.
Solution
Replace furnace control (IFC).
