A/C blowing warm and cold air?

This sounds like you have an A/C compressor going out, but to be sure let's get a reading on the pressures when the engine is at 1,500 RPMs.

This video will help:

https://youtu.be/4EqdrBVb0sY

This guide can help as well:

https://www.2carpros.com/articles/comprehensive-guide-troubleshooting-intermittent-automotive-air-conditioner-problems

If the compressor is okay and the outlet pipe from the evaporator is cold at the firewall you may have a temperature actuator that is going out here is the location so you can check it out. Check out the images (below). Please let us know what you find. We are interested to see what it is.