Strange heat pump problem.

[Rich Riesmeyer]

Sitting in my primary residence last night, and heard the blower come on for the central A/C. But it wasn't supposed to, it just came on out of the blue.   I turned the system off at the thermostat and the blower kept running.   I had to shut off the breakers for the system to get the blower to quit.   Can anyone give me a starting point to troubleshoot this?   I will probably have to call in a pro., but wanted to see if there is anything I can do myself..TIA