Any noise accompanying this "hard to turn" problem?? Check the fluid level to start with!! If low the fluid can/will permeate the old hoses and loose fluid, over time, without showing signs of an actual leak. Consider flushing the system and replacing the hoses. That fixed mine!!
I have seen different fixes with this condition; When the steering won't turn one way or the other when it's cold, it has been an issue with the steering gear and /or the pump. The issue with it hard to turn when it is cold could be one or the other, but lately I had some that a good flush of the power steering fluid did the job, and some others needed the pump replaced. Without looking at your car, I might suggest you drain and refill your system with fresh fluid and conditioner first, if the issue still continues, then replace the pump. By changing the fluid first would be very good, because that will at least clean the system before replacing the pump, which will remove contaminants from your system so the replacement pump will not get contaminated when installed. Good Luck. Sorry PR takes me longer to type,oops