The ac system does not function. I like to perform the work on my volvo myself rather than take it to a repair outfit. I bought a black light from walmart for $9 canadian and this successfully showed two leaks adjacent to the bottom of the condenser - one at a sensor port and the other at the connection point between the condenser and first aluminum pipe (both condenser and pipe are less than 3 years old). The ac worked 3 months ago, but will not work now. I have concluded that it needs recharging.
My questions surround the necessity of applying a vacuum to the system prior to recharging, and if I do have to apply a vacuum what is the most cost effective way. I would assume that if I just refill the system with 134a and include a can that has a leak sealer that this would be ok without applying the vacuum because there is little chance of moisture laiden air getting into the system. Now, if I replace the two "o" rings and take say 5 minutes to do so will I need to apply the vacuum.
I have seen various vacuum pumps on e-bay- and have also seen something called the mighty-vac, which seems to be a hand operated devide.

I would really appreciate comments from folks that have completed such a procedure.

Thanks