Ah, see the group hasn't lost its edge.
I have a York Stellar Plus, model P1UDD12N09501A with a Honeywell Chronotherm 3.
The fan works, as in I can turn it hard on at the stat. However, the fan never comes on in auto mode. The stat trips, the firebox lights, but never a fan. It used to take a couple mins from fire to fan.
I guess there is a temp relay/sensor that died. I want to replace it myself.
Tips, suggestions and, of course, comments.
Thank you to the guy who answers.