I have a 2007 S40 2.4 with around 160lk miles on it. The issue I am having is when the weather gets cold(60F & below, worse at lower temps) my power steering sticks in the center. Its super tight when I try to turn, then it will "snap" all of a sudden causing the car to jerk to the direction I am trying to turn. Turning back & forth multiple times will keep it free but if it is left centered up for a moment it will stick again. I have seen some people suggest sucking out the fluid & replacing multiple times but I can't find a lot of info on my exact car.

 

refreshing the fluid is pretty easy - I'd do it as a baseline. I use a turkey baster with a section of rubber hose attached to suck out all the fluid from the reservoir then refill (standard ATF like Dex/Mercon - one quart will do it). start the car and go lock to lock a few times then let the car idle a minute or two then stop the car and repeat. After about 3 or 4 times your fluid will go from dark brown to red. Once that is done give it a drive around town, check the level again and color. At that point you should be 75% new fluid and now you can see if the stickiness is still there. If it still feels sticky then you'll need to have the suspension parts inspected (tie rods/ball joints ) to make sure they are not binding or worn etc. After that the problem would likely be in the steering rack.

 

I agree (as usual) with mt6127 - check (ASAP) for some sort of serious wear / looseness / interference in the steering components (including ball joints), then suspect the steering rack. It might be instructive to put both front wheels in the air to see what it feels like - with any luck you'd be able to find the source more easily that way.