Over time, the seals and connections in your vehicle’s air conditioning system can allow a small amount of R-134a refrigerant to leak past and escape into the atmosphere. During cold weather in particular, the rubber seals shrink and provide a less secure seal. Adding R-134a refrigerant to replace the leaked refrigerant can be done at home by the average do-it-yourself mechanic for a fraction of the cost of paying an auto repair shop to perform the procedure.
Attach the gauge set to the service ports located on the high-pressure and low-pressure aluminum a/c lines. These ports are found on the passenger side of the engine compartment in most cases. The blue hose of the gauge set is attached to the low-pressure port, and the red hose is attached to the high-pressure port. On vehicles equipped with R-134a refrigerant, these ports are a standard size and the hoses cannot be attached incorrectly.