OK this is where have the full set comes in handy. If the low side doesn’t drop, or drops only a little, you could have a bad compressor or the system could be clogged downstream. With a high side gauge, if it is a clog downstream, the high side will go very high. If it doesn’t go up much, that would be the compressor.
Youi might also have a problem with your blend door allowing heat into the ducts. Common issue with GM, in fact I’m about to install a new blend door actuator on my Chevy for this very reason.
If you don’t have a cabin air filter, you could have a build up of gunk on the evaporator core, had a Honda that this happened to. So many things to go wrong.
Edit: If you go tearing into the system, you should at least take it to a certified AC shop and have the refrigerant removed. That is the responsible thing to do instead of dumping it into the atmosphere. When you recharge the system, you will need to get a vacuum pump to pump all the air out of the system before you introduce new refirgerant. You can get a vacuum pump from Harbor Freight for under $100.