furnace ignites then after 10-25min cuts off

[hvac86]

Rookie tech working on a Sears brand furnace model 867.764221
The furnace comes on and stays lit for 10-25 min then shuts off. has a spark ignition that is also combination with the flame sensor. Is it a dirty flame sensor with a combination of a failed spark box? Used my multi meter and also turned on furnace disconnected
the flame/ignition sensor write and

[snupytcb]

are you sure it is not tripping high limit? or even satisfing t=stat?

[Rammerjammer]

Sounds like high limit like snupytcb said. Check airflow. Dirty blower wheel. Dirty filter or stopped up evap

[kw10925]

you should check air flow,make sure its not shutting off on high limit.Also make sure that prving switch is not loosing its draft ,may have clogged tube on the inducer.

[craig1]

Is this a condensing furnace? The drain could be clogged and backing up.

[Dowdhvac]

Check unit for proper gas pressure, furnace will tell you the minimum gas pressure required for the furnace. But like the other guys said, check air flow, flame sensor & check to see if you have proper draft.

[doc havoc]

If it's running 10-25 minutes, I highly doubt it is a flame sensor or control board issue. As others have stated, cycling on limit, satisfying call for heat at the stat or plugged/restricted condensate drain.