Yesterday was 94F here and I noticed A/C system on 04 Camry was not cooling as in summers past. Compressor is engaging and low pressure line is somewhat cool to touch but not cold and sweaty. I usually have an A/C thermometer stuck in the middle discharge vent but haven't got around to installing it yet so I don't know what discharge air temp was NOT cold enough for sure for my wife. All fans functioning normally. Local Toyota dealer and another shop want to completely evacuate system/dehydrate and then refill R134a as measured on a digital scale. Something about EPA regs. My question is: are the A/C refill kits accurate enough to just add refrigerant? I have the gauge and hose setup from a kit I purchased years ago. I'm considering purchasing a can of R134a without sealer and adding enough to get the gauge reading in the green.I realize that A/C service is best left to trained techs, but vehicle is on 18th summer cooling season and I'm weighing cost of purchasing a new vehicle. My war department is very,very much bothered by hot weather and I don't want the #@&^%$@$^ about a hot car. Advice appreciated.