For anyone interested in learning how the late 60s / early 70s GM Frigidaire factory AC system works, I made an in-depth 30min video explaining how it all works in my 70 Nova.

In the video, I explain how the factory AC system operates and what's needed to update the system for R134a.

Explanation of controls 0-10:20
Driving test 10:20-12:55
Underhood components & purpose 12:55-25:36
Whats needed to use R134a 25:35-33:32
Factory AC vs aftermarket 33:32-end



I also made a few videos to help with flushing the evaporator and testing/adjusting the POA valve:
Flushing the evaporator: https://youtu.be/vMpsEwh7Uqg
Testing the POA valve: https://youtu.be/PhWW7hD9-Yw
Adjusting the POA valve: https://youtu.be/B95_q7Z8DIE

I hope these are helpful to others!