[s-cars] Recharging AC

[Calvin & Diana Craig]

What is the proper procedure for adding refrigerant into the A/C system.
The last time I did this I kind of just watched a friend and didn't pay much
attention.  I know you put it in the low pressure port, which I believe is
on the belly side of the compressor.  Should the AC be turned on and
running?  What should the low pressure side read, ideally?  I have heard
somewhere around 30 psi...is this right?  Thanks!

--Calvin