To find it, you should:
1. Consult your owner's manual: This is the best place to start. It should have a diagram of the fuse box and relay locations.
2. Check the underhood fuse box (PDC): Open the hood and locate the large fuse box, usually near the battery. Look for a diagram on the inside of the lid that shows the location of relays. Many relays are interchangeable, so you might need to visually identify the correct one (it will likely be a larger relay than others, potentially labeled "cooling fan" or something similar). If you have a multimeter, you can test continuity across the relay's terminals while the engine is hot and the fan should be running to be sure.
3. Look near the battery: Sometimes, especially with optional equipment, additional relay centers are placed near the battery. Check this area thoroughly if you don't find the relay in the main fuse box.
4. Online forums: Search online forums specific to 1999 Chrysler Town & Country vans. Owners often post pictures and descriptions of their relay locations. Be sure to specify your engine size (3.3L or 3.8L) as this might make a difference.
Caution: Working with automotive electrical systems can be dangerous. If you're not comfortable doing this yourself, take your van to a qualified mechanic. Improper handling of electrical components can lead to damage to your vehicle or personal injury.