Why does my AC continue to blow air through the ventillation when t-stat is off, air is neither hot nor cold?

Question

I turned off my AC t-stat for the summer and while being turned off the unit will still continue to blow air the the vents

Answer 1

If it is cooling and heating normally it is likely a stuck fan relay on the furnace board (or air handler).

Some possibility it is a fan/limit switch on the furnace that is out of range and thinks it needs to cool down.

I would first remove the green wire at the furnace, or the one on the "G" terminal if not green,  (fan "on" control for running the fan only) off the board to check for a short in the wiring.

If that doesn't fix it is likely a relay.  

Good Luck.

Answer 2

Check the fan switch on the Tstat.

Should be on auto for automatic fan operation in heat or cool, or on for continuous fan operation.

If that's not the cause you should have it corrected by a tech.