I have a 95 Blazer 4 door 4x4. My 2hi light doesn't come on. Is this a problem?

Also, when I turn on the ac, after a few minutes there's a really loud and obnoxious screeching sound. Any input on what that might be?

 

the bulb for your 2 hi prolly blew out very simple change the whole switch just pops out the ac whatever it is doesnt sound good and i dont know

 

I remember reading something in the owners manual about if that doesn't come on, then you should get the car checked out.

The check engine light is on by the way.