The 1999 Dodge Caravan has two low pressure A/C valves, depending on the engine option. On models equipped with the 2.4L or 3.0L engine, the low pressure A/C valve is located on the passenger side of the engine bay, near the firewall. It is a black or silver cylindrical valve with a Schrader valve stem on one end.
On models equipped with the 3.3L engine, the low pressure A/C valve is located on the driver's side of the engine bay, near the air filter housing. It is similar in appearance to the valve on the 2.4L and 3.0L models.