I think air in the line will do nothing bu make a horrible noise. If it's hard to turn your car your probably low on power steering fluid, have your fron end greased up and make sure your level with fluid. If its still hard to turn I suggest having someone take a look at the front end
Could be a broken Power Steering belt or low fluid level or power steering pump failure.
A steering wheel may be hard to turn because the power steering fluid might be low. It also could be that there is problem with the power steering pump.
A few things could cause this. Low power steering fluid, too slow engine speed (low RPMs), faulty power steering pump or broken power steering pump belt, binding or poorly lubricated steering linkages, faulty steering gear, etc.
This problem could be cause by too much tension on your engine. The power steering is linked in with the rest of your engine pulley's and if you are demanding a lot from your power steering system it's going to in turn demand more from your engine and typically at conventional turning speeds your engine won't have enough rpm's or compression to continue to supply that needed power to keep the engine cranking and your power steering to be driven hard.
could be several places, power steering hose, rack and pinion (or steering gear box) or power steering pump.
It'll be hard to steer a car. The steering wheel will be tough to steer.
If you are talking about air bubbles in your power steering fluid?. The supply line to your power steering pump has a bad o-ring. This will cause you hard steering while engine is at idle.
It shouldn't be that hard. Maybe you are low on power steering fluid. Or the pump could be bad.
Check to see if power steering fluid is at correct level Could be belt is glazed and slipping Could be a bad power steering pump Could be a bad steering rack Could be worn front end parts
Sounds like an issue with your power steering. Since there's more than one possible reason why this could be happening, you'll have to do some troubleshooting to figure out the cause of the problem.
The obvious: It will become very hard to steer. The not so obvious: The power steering pump is lubricated with power steering fluid, and driving it dry could damage the pump.
Sounds like bad power steering pump, but could also just be the power steering pump belt is slipping.