What does it mean when the heat only worked on high, twice??

I was driving and had the heat on high, switched it to the next lower setting and it shut off. No other settings worked, but within 15 mins, it worked fine again.

This happened 2 different times and worked fine within 15 mins and no problems since.

I haven't seen anyone post this same problem before so thats why I ask.

Tony 1998 SVT Contour (B/MB) #542 3L 1998 SVT Contour (SF/MB) #1266 parts car 2000 SVT Contour (SF/MB) #1533 3L swap to begin!