Mondeo Mk4 power steering is intermittent

[pumpkindonut]

There seems to be a strange problem with power steering - when I start up my Mondeo and take off, then steering is quite light (as it should be) 

But when I have driven some miles, then the steering becomes heavy. Even at low speeds. E.g. when maneuvering to parking space,  the steering is too heavy to turn the wheel with one arm.

 

I assume steering should be always light.

 

Does anyone else experience similar problem and what could be the possible cause?

 

PS! Car has 49 000 miles on the clock.

[jeebowhite]

sounds to me like a problem with the hydraulics system - have you checked the fluid level for the power steering fluid?