[M_a_t_t]

Since you are in California, you probably know exactly what I am talking about, but here it isn't "standard" yet. The small cans of r-134a that have a valve in them can be used to evacuate the system too. You can rent a vacuum pump from the LAPS and use those smaller cans (for example: if you have been refilling because of a small leak) to hold the freon that is left in the system. Then replace o-ring or hose or whatever. And then use the freon in those cans to refill it.