The blower on my Goodman gas furnace came on all by itself tonight? Every 5-10 minutes the blower turns on for approx 1 minute then turns off by itself. Then the cycle repeats.

I verified that the thermostat is in the off position (no heat/no cool) and that the fan switch was set to auto.

I have checked wiring behind t-stat and disconnected t-stat completely. Blower still appears to be haunted.

Nothing new has been installed or repaired recently.

What might cause the blower to auto cycle like this?