Automatic transmission fault

My car takes off from start real slow, then it does not shift into any other gears. I believe it is stuck in third. it tacks at 3000 going 64 mph so tends to have cooling fan on always. I have reverse and drive without hesitation, just the transmission stays in same gear no matter where the shifter indicated is.
Also, at same time this happened my air conditioner is now blowing warm.
Can anyone help?
Thank you