I have a trane gas furnace. When I turn it on it blows cold air. I opened the panel and saw that its not lighting. Thanks for any imformation.

Good morning.

Does your furnace vent with plastic or metel pipe?

The bottom pannel should have I sight glass in it. Look in there and see if you see a flashing light? Count the flashs

Thank you for your response. It was 2 terminals on some kind of switch, mabe a limit switch. They were rusted so I replaced them and then sanded the igniter.
Thanks,
August