I have a rheem gas furnace model rglg 05nauer. Basically, it won't always light. The purge cycle works fine, then the ignitor glows, then it calls for gas. There are two gas nozzles, one goes to the ignitor and the other to the flame sensor. Gas will flow to the ignitor nozzle and it will light, but most of the time the other nozzle won't light. Then, after about 5 seconds it will shut down. Help! It's getting cold in here.

Double check your furnace model # it doesn't look right. You should have a flashing light on the control board telling you what part is at fault.

Thanks for the reply, but I found a furnace repairman in my area and he told me what is wrong. I now have it fixed. The gas crossover was dirty, so after I cleaned that it works great.