in re: Funola & 97SL320/valve core removal

In the R-12 days I used a tool that allowed you to remove the valve core w/o losing gas, and then replace it post evac & fill. Haven't bothered to get one for R-134A automotive ports.

Core removal made dye & oil injection easier, and cleaner. Long vac pulls are good if you have the time, but ambient temp is also very important. The purpose of a 29.9mmHg vac is to drop the boiling point of water to just below 70F. The modern technique is to have a micron gauge and to use your 'super duper' pump to pull down to 400 microns or so. I cheat. I use a heat gun while pulling a vac. I heat up all the metal bits to help the evacuation of moisture. If I am certain that moisture got into the system, I have been know to inject 90% isopropyl alcohol (small amount) & then draw it thru the system (reverse flow). The theory is that the alcohol will attach to the water and as a solution will evaporate more quickly while using vac & external heat.