My air started blowing a little warm so I bought freon r134-a to charge it?

We need to start with what the pressures are in the system.

The pressure in the system will tell us what the possible issue is and what direction we need to take.

Here is a guide that will help with this:

https://www.2carpros.com/articles/re-charge-an-air-conditioner-system

Once we know the pressure, we will be able to better determine if it is just low on charge or there is a greater issue in the system.

Please get the pressures when the compressor is off and then what if goes to when the compressor is on.

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

I attached a chart below that will show what the possible issue is but if it is low on Freon then we need to follow this guide to do that:

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

Please see the chart below and let us know what you find, and we can go from there.

Thanks