All vehicles manufactured after 1995, including the 1999 Dodge Dakota, use R134a refrigerant to keep their AC, or air-conditioning, running cool. Over time, most air-conditioning units loose their refrigerant and eventually blow semi-cold air. Refilling your AC unit used to be expensive and you had to go to a dealer. However, you can now purchase a do-it-yourself refill kit from most popular auto part retailers and refill the AC in your 1999 Dodge Dakota yourself.
Thread the recharge service hose to the can of refrigerant. Turn the knob clockwise on top of the service hose to puncture the seal in the can. Turn the knob counterclockwise a small amount to push air out of the hose and then turn the knob clockwise to close the valve.