A Trailblazer that squeaks only when turning to the left could have a problem with the steering or front wheel bearing. Turning to the left puts the right pressure on the parts to cause them to squeak.
Many things can cause that, the simplest cause being lack of power steering fluid.
Try checking the power steering fluid. My taurus did the same thing until i filled the power steering fluid.
Does this squek vary with speed? When stopped and turning right does it squeak? More info is needed
Most likely the steering linkage. (Tie rod ends etc. ) They are short of grease. Have the front end checked. If the parts are original Ford, then you will be unable to grease them, just replace them if they are worn.
Turning to the right, when going forward, you turn the steering wheel towards the right.
The cause of the squealing sound is because you are turning the steering wheel completely to the right or left
Power Steering pump my have a leak...
Power Steering Pump
Turning the steering wheel farthest left or right for a few seconds will cause a loud squealing.
The back of the PWC is pushed to the left when a PWC's steering control is turned to the right.
If the sound is a loud growling , whining, noise you're probably low on power steering fluid. Now the cause of the fluids loss is WHERE ?