A/C system evacuation

[pmizell]

The leak in my R-12 system was found to be at the expansion valve. I'll be replacing it soon, along with the receiver/drier and hopefully restoring my A/C system to like-new.

After replacing those components, I'm going to completely flush the hoses/evap/condenser and remove/refill oil in compressor and close the system back up.

At this point, from what I understand, I need to pull the system into a vacuum to remove any moisture prior to recharging.

I bought a "venturi-type" vacuum pump for this purpose, (Harbor Freight, hooks up to compressed air) and advertises a vacuum of 28.3" of mercury --- 4.2CFM consumed. <----not sure if that means pulled.

My question is: is this sufficient vacuum to properly remove any/all residual moisture in the system?

I really don't care to pay $150 for a 2-stage vacuum pump to only use once. Can these be rented somewhere?

Thanks for any insight you can provide!