Borrowed an AC manifold set from work and a Vacuum pump from my brother-in-law to get the AC system charged. We have never done this before, and had a hard time finding good step by step instructions. Had to watch several painful youtube videos. If you are not familiar with this process, here are simplified steps to properly charge an empty system:
1. Connect the hi and low pressure side lines (they only go on one way) and screw in the knobs to open the Schrader valves. Both valves on the manifold should be closed
2. Connect the yellow line of the manifold to the vacuum pump (should be rated to 29" of Hg in order to boil off the water in the system at room temperature), turn on the pump, open both manifold valves
3. Vacuum the system for a minimum of 1/2 hr, if gauge doesn't get to 29" of Hg, you have a leak.
4. Close the manifold gauges, shut off the pump, watch the low side gauge for 1/2 hr, it should stay at 29" of Hg, if it doesn't, you have a leak, ours was rock solid even when left overnight.
5. Disconnect the yellow line from the vacuum pump, and attach a can of 134a and open the can valve to allow the refrigerant to flow, I found a $3 can adapter at autozone, that will open the can valve when you attach the line.
6. Start the engine, AC on, Fan on low.
7. Open the low pressure manifold valve (Blue) and invert the refrigerant can to allow the liquid refrigerant to flow into the AC system. AC compressor will cycle on/off and the hi side pressure will build as it does.
8. Add 1.25lbs (20 Oz) of refrigerant. I weighed the cans to know what I was putting in. You can also watch the pressures (preferred method) according to ambient temps and pressure tables in the service manuals, but since my garage is cold now, I went with simply adding the proper refrigerant weight.
9. Close the manifold valves, close the Schrader valves, disconnect the lines, put the caps back on, engine off
AC system charged... $13...