My AC unit runs hot air for half an hour before cold air comes out,.
My 2001 Frontier AC unit runs hot air for half an hour before cold air comes out, and when it does the pressure is good too.
could be a bad compressor etc. Start off with making sure you have enough refrigerant.
With AC’s it is hard to make a determination since it requires the proper gauges and testing equipment to do so. Consider having it checked (diagnosed)by a AC shop.
Here are some ideas for the basic testing
If you want to go all out, this will definitely help you if you can get the tools. Frontier-HVAC.pdf