Just bought it and installed furnace yesterday
It lites and runs about 1 min,than the flame goes out and the plenum only gets luke warm. It blows cool air
Thanks.

Did you install it? If is brand new you could call the manufacturer and have them send out someone to troubleshoot/fix it if we can't figure out your problem.

Who is the contracter that installed it? Call him back out to finish his job. I hope someone that is not a certified goodman tech installed it,, you may not have a warranty if that's the case.

wmproop is exactly right. If you installed this unit yourself then you are SOL on the warranty. Call in an EXPERIENCED, QUALIFIED service company.