The furnace worked fine for a week,now when I turn it on the blower begin to blow, the ignitor glows red showing it stills works fine, I even hear the gas but there is no flame. This cycles about three times then the furnace stops and warning blinks once which is the ignitor warning but the ignitor works fine

You should clean the flame sensor with steel wool or fine grit sand paper and if that does not work test the flame sensor by following the attached file. Note some special tools are required for testing.

If you are certain of gas delivery, something is obstructing the burner passage, or the ignitor is out of position. Check burners for build-up and/or webbing.

No luck, I cleaned the flame sensor even bypassed the blower motor switch. One service tech had me check the flute for birds. Still nothing, I think I'll try cleaning the burners but should I detach them or use a flex wire brush or what? What's safe ?

You should clean the flame sensor with steel wool or fine grit sand paper and if that does not work test the flame sensor by following the attached file. Note some special tools are required for testing.

No luck, I cleaned the flame sensor even bypassed the blower motor switch. One service tech had me check the flute for birds. Still nothing, I think I'll try cleaning the burners but should I detach them or use a flex wire brush or what? What's safe ?