furnace go into lock out

[Riolenny]

I have Snyder General gas fired-upflow furnace. It will lite but only run for seconds the fan never comes on. After several attemp it goes into lock out. I think it the fan & limit control or the gas valve control. Any help will be appreicated.

Thanks.

[HayZee518]

why do you think its the fan? the fan just circulates the hot air. I would be more inclined to check out the flame sense circuit for the main valve. check out the thermocouple which should be in the pilot flame.

[Riolenny]

Thanks. I will look at the flame sensor.

[Riolenny]

The new flame probe sensor worked. But now the fan will not kick on after the flame starts. I can turn the fan on cont. and it will come on just fine.
Any ideas are welcomed.

Thanks

[HayZee518]

the fan is controlled by an air plenum switch. basically it's a coil that is in the air stream and expands and rotates closing a set of contacts. the contacts can be set for minimum temp and a max temp band.

[Riolenny]

HayZee thanks for all the help. Everything is works fine now.

Thank again.