* Consult your owner's manual: The manual will have diagrams showing the location of all major components.
* Look at a diagram online: Search for "1997 Chevy Blazer A/C compressor location" on Google Images. You'll find several diagrams that can help you pinpoint it.
* Visually inspect your engine bay: Once you have a general idea from the above, carefully look at your engine bay. It's usually close to the alternator and power steering pump, and is easily identified by its size and the refrigerant lines connected to it.
Be cautious when inspecting your engine bay. The engine and components are hot after running, so allow time for cooling before working near them.