The fire box is lighting but the furnace fan doesn't come on. Where
is the temp relay? I've got a York Stellar Plus, Model P1UDD12N09501A
with a Honeywell Chronotherm 3 stat.

I assume the whole circuit is in the furnace itself BUT it could be in
the stat as well. I know I can turn the furnace fan hard on at the
thermostat. Maybe the York return a firebox temperature signal to the
C3.

Thanks