Trane gas furnace, at least 11 years old, mounted in attic. Earlier tonight it started making a "clunk clunk" sound, followed about three seconds later by a fainter single "click". A couple of seconds later it starts again with the "clunk clunk."
Turn the furnace off and everything stops. Wait a few minutes , turn it back on and the cycle starts again. After an additional 30 to 60 seconds the fan starts But, there is no light-off - no flame.
Can't tell where the "clunks" are coming from. It might be the gas valve. With my hand on the gas valve a vibration can be felt there with each clunk. The 'click' seems to come from deeper inside the furnace.
Any suggestions or ideas? Thanks.
