To find out if yours has one, and where it might be:
1. Check your owner's manual: This is the best place to start. If a cabin air filter was installed at the factory, the manual should show its location.
2. Look behind the glove box: This is a common location in many vehicles, but not guaranteed for your Ram. You might need to remove the glove box to check.
3. Inspect the area under the dashboard, near the blower motor: This is another possible location, but access may be difficult.
4. Consult a repair manual specific to your 2001 Dodge Ram model (1500, 2500, 3500): A repair manual will provide detailed diagrams and instructions.
If you can't find a cabin air filter, it's likely your truck didn't come equipped with one from the factory. Adding one is usually straightforward with an aftermarket kit, although you may need to create a space for it.