Power steering going in and out

I have a Nissan '04 Altima. Last winter, in temps near zero, my power steering seemed to go out. It worked fine when it got a little warmer. Figured maybe a stuck valve or something on the pump. Works fine sometimes and sometimes it doesn’t. Asked my mechanic to check this out when I went in for my last oil change. Not sure they checked anything (it was working when I brought it in) they recommended a fluid flush. Did the fluid flush, it continued to work for a few days, then stopped working again. Just wondering if anyone knows what could cause this so I can have them check specific components. And so I don’t spend money on things that I don’t need to. Thanks

This could also be indicative of a worn or damaged steering rack.

Because this is a potential safety issue, I would suggest that you make it a priority to have the rack & pinion checked.

Thank you, thought it was something like that. luckily I don’t have to drive it much, I will get that checked.