Ready to pump down and charge my AC system this weekend. How much 134A will the system hold? After I pump down I will start car. Turn AC on high with blower on high speed and fill.

Thanks once again for your time..

None, a stock system should be running R12.

Thanks alot.. that is not an option

The typical rule of thumb for conversions is 80% of what the r12 capacity was, ie. 3 lbs of r12, you would charge 2.4 lbs of 134a.

Also, r134a has a tendancy to seep through r12 hoses over time. You may want to consider having some new ones compatible with r134a made up. I'd also change the drier and drain the oil from the compressor and add synthetic PAG oil which is what the r134a systems like. Doing anything other than the above may result in some issues down the road.

Good luck, and let us know how it goes.

Agreed Doc. You will want to have 134A agreeable hoses. You will also most likely be ahead of the game if you flush all of the old oil from the system.