If the steering wheel is hard to turn at low speeds, this problem is a good indication of the faulty power steering pump.
If the car is equipped with power steering, a power steering system has something called a "power steering pump" - a device that pumps power steering fluid through various tubes/valves, thereby creating hydraulic force. This hydraulic force is then applied to the steering gear, making steering easier for the driver (hence the term "power steering").
The most likely cause of this particular problem is that the power steering pump is (occasionally) failing. Specifically, if the pump stops pumping for a moment, there will be no hydraulic pressure (during that moment) and thus the steering will momentarily become stiff.
Another (but rare) possibility is the following... if the power steering belt becomes wet, it can slip and cause the steering to be stiff (while the belt is slipping). The belt can become wet if the vehicle has been driven through one or more deep puddles of water.
What to do?
You'll need to have the power steering pump replaced. But first, just to be sure, go to a repair shop and ask the mechanic to inspect the power steering system. Have him confirm that the cause of this problem indeed lies with the power steering pump. When talking with the mechanic, explain to him exactly what we explained to you. This problem is potentially hazardous. Therefore, please have the necessary repairs done soon.
