I have a Janitrol ac unit in my house, and it is not blowing any air out, but has been running all day. I checked the unit that is outside and it is blowing cool air, not warm. I just replaced the air filter too, could it be low on freon?

Could be your compressor is not running, could be low on freon, could be you have a leak, could be dirty coils causing compressor to over heat and shut off... could be lots of things. Might want to have a tech come take a look at it.