Auto Air Conditioning & Heater Repair: A/C Booster, subbaru, subaru legacy

Question
Hi Dave,
   Last year I bought a can of auto A/C booster with dye from napa for 2 differnt vehicles ('93 plymouth grand caravan and 97 Subaru Legacy). It is suppose to make your sysytem up to 18% cooler. In both vehicles I lowered the Presure first, added a can than brouht the pressure back up to 35#'s with R134a so that I would not over charge it. It ran OK last year but They both stopped working this year. The preesure is higher than what I set it last year (high 40's). I bled it down to 30#'s and it came out foamy and they both still will not blow cold air. My question is, is this stuff OK to use or does it cause dammage over time and how can I correct it. The Subbaru is making a continues clicking sound only at idle.Thanks.

Answer
I have never used any thing like that    sounds like the subu compressor is going out   the caravan is a single unit or dual? duals run higher low sides   temps and humidity effect low side perssures they run a little higher the hotter it is outside need to check those high side readings to insure proper charge