so i got home today and found my vents were still blowing full speed when I turned my car off, i even double checked to make sure the key was in lock position. I turned the hvac to off but it just kicked on the ac at full blast. turned the fan to low and it killed it. Any ideas on what might cause this.

-ps I know cooling fans may run after car is off but these are not the cooling fans.

 

Check to see if the relay is sticking closed. unplug the relay if it goes out, it might be the problem. swap relays with a known good one