AC blows out air but it is not cold

Hello, I am Danny.

Have you noticed if the compressor is cycling? When was the last time the A/C system was serviced (refrigerant added)? The system has a cut-off switch that shuts the compressor off if a low level of refrigerant is detected. That is to prevent damage until proper level is corrected. I have attached a few tutorials for you to view.Hope this helps and thanks for using 2CarPros.
Danny-

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

https://www.2carpros.com/articles/air-conditioner-leak-detection

https://www.2carpros.com/articles/air-conditioner-how-to-add-freon

Okay, so when I turn on the AC it does not make a squealing noise. Do I put the AC charge on the low port with the car on and AC running or with the car off?

Hello again.

You add to the low side (only fits on that port) with car running and controls on Max A/C. It may take awhile it enters slowly. Hope this helps and thanks again for using 2Carpros.
Danny-

https://www.2carpros.com/articles/air-conditioner-how-to-add-freon

The gauge reads zero when it is off or on with AC on max.

Hello again.

It usually takes a while if using a recharge can for enough to enter to get the compressor to cycle. Has the A/C been working recently and then quit? It is also possible you have a major leak in the system. I have attached a tutorial show leak detection. Hope this helps.
Danny-

https://www.2carpros.com/articles/air-conditioner-leak-detection