Having issues with AC:

Started with adding freon. Used one of the pro ac cans with yf1234 kind a while back and nothing changed was blowing hot air. Sat for a while, then I started looking into things. It does have a rear blower.
Was blowing hot air on drivers side, not as hot on the passenger, and somewhat cooler in the back.
1. Changed the blend door actuator. Drivers and passengers side runs same temp but warmer than rear.
2. Put manifold on checking pressure and adding some freon to see if I could optimize.
a.) Compressor isn't making bad noise, doesn't shut off, but wouldn't in my logic if it doesn't hit temp controls are set to.
b.) Pressures were good but drop when back is turned off. (Reading around 43psi low and 175psi high with rear on, actually both then closer to 30psi and 145psi on the high with just front AC when rear turned off. I didn't check with just rear running.)
c.) The freon didn't change the front ac pressure much at all (from starting point) so not sure if it would be trapped on the rear system or where else it would go unless there is a leak that was pressure sensitive yet doesn't make sense as pressure goes up with rear engaged.
*So question(s) is what's can I troubleshoot from this info.
Is there an oriface/expansion valve issue? This is my guess from behavior of pressure, but I don't know the system and how it works to a T by a long shot.
Evaporator coils dirty?
How many components are there separately for the front and rear system?
Any of the sensors high pressure, low pressure, other as I'm not sure of all?
I couldn't see any fuses that would help either.

If this seems a familiar problem anyone has solved let me know, save some time researching...thanks

It has other problems that shouldn't be related, but shutter grill issues, and evap cannister, fuel system....just in case there is any correlation.