A/C Charge by Myself

harrisonm said
I was wondering about charging My AC system by myself. I have a vacuum pump I use for brake bleeding and gauges that will allow me to add R134. I have a 69 Barracuda with a Classic Auto Air unit that had to come out for paint. It is all back in now and ready to charge (yes I replaced the drier and all O-rings). Why couldn't I just vacuum the system down as much as possible and put R134 in myself. It isn't so much the expense; I just hate to drop my car off and go back to pick it up later. the few places I have called basically said just drop it off and we'll call you when it is done. I was thinking on putting in about half the charge with the AC compressor off, and then finishing the charge with the motor and compressor running. Thoughts?

As the others stated, a brake bleeder vacuum will not do it. Ideally, one would wish to evacuate the system to 500 microns or less. That would equate to more than 29.9 inches of vacuum. That is some serious suckage and most typical shop recycler machines will not do it, nor are the analog gauges accurate enough to determine a precise reading. It needs to be evacuated to boil all the moisture out, otherwise it will not work at the most efficient level. Moisture in the system is not condenseable and if enough exists it can actually freeze at the expansion valve when the refrigerant undergoes a endothermic reaction as it changes from a liquid to a vapor state.