You just have to rely on the pressure in the bottle to get enough in there until the pressure switch sees enough to start cycling it. I am assuming you are using one of the recharge kits shown in the link?
Normally you can put enough in with the engine off and then start it and that should have been enough to get the compressor to turn on.
Let me know if this guide doesn't help and we can go from there.
https://www.2carpros.com/articles/air-conditioner-how-to-add-freon
FYI - if this is a new compressor, I would highly recommend using an AC machine because you need to add oil in as well as freon unless the compressor came filled. These recharge kits cannot do that.
Saturday, February 29th, 2020 AT 4:04 PM