If you have studied a/c systems or watched a pro service a/s systems you may want to tackle it yourself. You can buy a Haynes A/C and Heating Systems manual and a Professional type manifold gauge set. If the pressures are not normal you can seek professional help. If you need to open the system to replace parts you need a pump to evaporate any moisture in the system. The pumps are expensive. It will eventually kill the system if moisture is left in the system. The r134 professional gauges are not that expensive, especially if you want to experiment and learn. If you read up on it,it is not rocket science. Have fun.

__________________
1990 190E 2.6
1996 Grand Voyager 3.3
1985 Mustang GT 5.0 5 SPD
1982 Suzuki GS 750T