How do I know if my AC needs recharged?

How do I know if my AC needs recharged? Welcome to Mercie J, where compassion and craftsmanship come together, I'm Rick Smith.
So typically, we're going to notice that our air conditioning isn't blowing as cold as we like. First thing I want you to do is switch hot to cold to make sure the heat comes on and heat goes off. If it doesn't, then we might have a problem with the doors inside the car.
Secondly I want you to make sure when your engines running, if you have an electric fan, that the electric fan is running out by the radiator. If that's not working, you're going to have some problems.
Now let me show you how you're going to know if your refrigerant seems to be in the general level or not. So we're working on a Chevy Silverado here and the first thing you're going to do is you're going to look with the engine running and air conditioning on and make sure the compressor's turning. If you don't know what that is, I'm not sure how to help you on this video, but if the compressor is turning then you're going to have two lines coming out of your firewall one is large and one is small. Do not touch the small one, it will be very hot, but you're going to feel the large one. The large one, whatever temperature it feels that's exactly what to be happening inside the car. So it should be around 40° coming out of here. If it's only cool then probably the refrigerants a bit low or you have a valve problem inside the system.
I hope this has been informational for you and until next time safe travels and blessings to you.

[@markm0000]

A good trick is to put one pocket thermometer in the air vent and one under the dash near the inlet. If the AC starts blowing really cold suddenly it’s losing refrigerant. Do not let it run like that it is damaging the compressor. Make sure both thermometers are reading the same temps at ambient and in ice water.

[@tbone6354]

A good idea is to add 50ml of water to the compressor before regassing then no need to vacuum

[@MercieJAutoCare]

The primary purpose of pulling a vacuum is to remove moisture.