TURTLE wrote:
This is Turtle.

It would be nice to know a model and serial number of it and about how
old is it.

Was it made before 1991 or made after 1991 ?

Does it have a vent fan that blows when the flames comes on. ?

now I will take it that it is a older model made before 1991 by GMC.

You have a fan/limit switch sticking. Change or read ajust the
fan/limit switch. if labor cost is high in your area , change the
fan/limit out with a new one.

Now if it is a GMC furnace made after 1991 or maybe 1993 that is
another horse of a different color. You need it looked at NOW and not
later. It could burn your house down doing this.

Reply with answer to the above or i answer e-mails too.

TURTLE

Thanks for the reply Turtle!

It is a GMC, Goodman manufacturing, model GU100-4, REV A,S Serial
Number 900281904. I could not find a manufactured date. I only know it
was here when I purchased this older home. There is an ANS date code it
appears of 1988?

Wow, fan limit switch. I was thinking something like gas valve since it
was staying burning after fan shut down. Im sure glad we have
knowledgable folks to help us from making stupid mistakes! THANK YOU!

Fordtech