To be absolutely sure:
* Consult your owner's manual: This is the best source for location specifics.
* Look for a service port: The low-pressure port will have a service valve (usually a schrader valve like on a tire) that you can attach your AC charging gauges to. It's usually easily accessible under the hood, often near the AC compressor or condenser.
* Use a diagram: A shop manual or online parts diagram for a 1997 Thunderbird can show you the exact location.
Important Safety Note: Working with automotive air conditioning systems involves refrigerants that can be harmful if mishandled. If you are not experienced with AC service, it's best to take your vehicle to a qualified mechanic. Improper handling of refrigerant can lead to injury or environmental damage.