Squealing very loudly at start when cold, and occasionally after that until it warms up, changed the alternator and power steering belt could it be the serpentine belt??

serpentine belt is getting old and hard and the cold weather was causing it to slip
check belt condition ( small cracks across the grooves = scrap and get a new one) and check tension

Squealing means the PS belt is loose or frayed. Replace the belt and adjust the tension correctly. The "bouncing" is caused by the PS pump starting and stopping because the belt is loose.

Hi Tereza.
has anybody checked the pressure hoses of the steering and especially the one which has the one way valve inside whether is the one with the problem?

So many mechanics, so little consensus. Sounds pretty common.
I can't say as to why hot and cold only when moving, but it sounds like a weak performing system.
As for the squealing, I would suggest removing one belt at a time, and see if one eliminates the squeal. That would be the problem belt or pulley or component. Also, if you have any idler pulleys (a stand-alone pulley) on the belt system, be sure and check them as well. Spin them without the belt on, and see if they make any noise.
It would seem you need a mechanic who is willing to spend some time with you on this to find the problem. When you find a good one, you will know it by his output, and make yourself a regular customer. Good luck.

Hello and thank you for asking me, the most common cause for this is a loose/slipping power steering belt so it should be inspected and adjusted or possibly replaced. This engine has two drive belts, one for the alternator and a/c and another one for the power steering, if one is worn or loose it's best to replace both belts. Let me kno wif you have any more questions or additional info.

Probably a slipping fan belt. Check the belt tension when it is very cold and see if one of the belts is loose. If so, loosen the bracket bolts to the alternator, power steering pump, or air pump (if equipped), and pry with a large wooden broom handle against the appropriate item until the belt is tight, then tighten the bolts.

The squeal is coming from the alternator belt, When the temp is low, the belt is hard and glazed and lost its ability to create friction.

check to see if the power steering pump is binding do you have the defroster on when this happens? if so it maybe the a/c compressor turn the defroster off and try to start it .

Try removing the belt and turning each pulley by hand. If everything is smooth and free, with the belt still off, drive down the block once and see if the noise is there (this will eliminate all rotating accessories on the front). If you hear the noise, then there is a problem deeper inside. Oil pressure is good? Dont' forget when doing this, you will have no power steering, so be careful.

The noise is most likely the serpentine belt. Check it's condition and that of the belt tensioner. It sounds like the belt is slipping, causing the squealing noise u describe. As the belt warms up, it's getting a better 'grip' and the noise stops. Turning on the heat also turns on the a/c in newer cars, this added drag on the belt (one more component to turn, the a/c compressor) would explain why it happens when u turn on the heat. Is the belt original? If yes, it's time to change it, and check the belt tensioner to make sure it's doing it's job of keeping the belt snug on all the pulleys. Let me know how u make out.