Furnace ac blower motor won't shut off?

Question

well... our daughter is kinda dingy... anyway, yesterday my wife & I had to run a few errands & we noticed the weather was nice, so she called our daughter at home to tell her to open the windows & turn the thermostat all the way up so the ac wouldn't run.

We got home 5 hrs later & she had turned it up all the way, BUT also set it to heat !!! Our house was like a sauna !!!

Ok, so flipped it to off & left the dial set to 85. It should shut off, right? nope. This am, left it on 85 & moved the lever to ac. it should shut off, right? Nope, it's been 15 mins & the blower is still running.

Now what do I do? Up to yesterday it was working fine. I can only assume that ac/heat switch has broken,

Answer 1

you have a low voltage short your little 3-5 amp fuse is blown the fan limit switch is overiding everthing more than likely contactor shut it off at disconnect at furnace and call a tech

Answer 2

i was gonna say check the fan switch....yeah it got flipped to on and not auto. DOH!

Answer 3

Is there a "Fan" switch on the thermostat?  Leaving is set to "On" as opposed to "Auto" will keep the fan running.  Depending on the wiring, the blower fan is operated by a couple of devices either of which could have contacts stuck in the closed position.