My furnace MMBA 090ABAR-01 with Ham Std 1018 series hot surface ignition continually goes through recycle of about two minets of running and 40 seconds of shut down. The actual burning seems to shut down after the blower comes on and then restarts and burns for something less than a minet. There is no blinking trouble light. Mild heating requirements are not a problem but cold weather is a big problem.