When I try turning my wheel, at some spots it gets heavy and stuck but it hasn't fully lost power steering? I changed the fluid. is it the pump or the rack and pin
My car has 255000 miles.
My car has an automatic transmission.
Those are two possibilities, but it may also be the struts and/or the upper mounts for the struts and the ball joints. This does not rule out the rack or the pump, but other possibilities that can cause the binding.
The vehicle will need to be fully inspected to see what is binding and the power steering pressures may need to be checked also. Sometimes the rack could bind in one position when turning, but the strut upper bearings or the lower ball joints may be binding also. The best test would be to lift the front suspension and see if the steering still binds from a bad rack.
If you need help with this, a certified mechanic from YourMechanic can come to your home or office to inspect your steering and suspension and perform any other services that are needed for you.