ENGLANDER room blower speed changes

[tonyiiiafl]

So far the Englander 25 insert has been doing a great job. However, I have it set for overnight at a 4 auger speed and a 5 fan speed. Every 6 or 8 minutes last night the room blower would change from the speed set to a high speed for 3 or so minutes, then back to the set feed. I even lowered the auger speed a couple of notches to a 3, but same condition. NORMAL??? A problem??

Also, what are these 3 buttons at the bottom of the control for and do?

Thank you.