I just added freon yesterday to the system. It fixed the whole cold left warm middle hot right issue. However, I don't think I ever got a accurate measure of the PSI. As I am full blasting the AC, and with the compressor running with ambient temperature at 88F, I have a reading of 40psi, I try giving it a couple burst or freon and PSI never moved... I gave a few more and still didn't move... so I ended up just feeling the cool air and I stop filling the system to avoid overfilling... I kept the bottle around just in case I need to give it a boost. What is your experience... am I having a bad gauge...

Ideally, should I be injecting freon on a super hot day or cooler day? Assuming my gauge is not working well.... My reasoning is to fill in hot day if I don't have a gauge to avoid the chance of overfilling in colder days when using the method of "feeling the air from the vents" What do you guys think?