Did you use a Dino 'UIB S' circuit board for replacement?
LED Green ON...all good
LED GREEN OFF----Limit switch, Sail switch or 5A fuse on board
LED RED ...gas valve open
S/B a timed delay relay.......
Red wire from the local On/Off CB on furnace frame goes to it
Blue wire from t-stat goes to it
RED wire from Relay goes to motor
Yellow wire from Relay goes to ground
See pg 10 (blower control board AND Time Delay 85-IV
Unless old circuit board was changed to a 'retro kit' board (with fan control on board)
Atwood #38676 (no Dino Board)