This furnace goes to lockout when running at 68 to 70 degrees; seems OK at 72 + degrees. Main blower has been renewed-confirmed and furnace was cleaned 5 months ago (not confirmed how well it was serviced though; by a technician.) If the furnace stops working, you can manually reset at SSU or just raise temp on digital thermostat (new stat, was a T-87F existing.) My thinking is the burner may not have been cleaned and I do not have the code yet from furnace. Any suggestions?