What are the cabin and outside temps? Your high side does not seem high enough, appears to be low on refrigerant

I stand corrected. My guy just said it was 45/190. It’s an R12 system if that makes a difference

Superheat is overlooked while focusing on pressures alone. You are looking for the delta between the hot pipe and the cold pipes at the evaporator and at the condenser. A competent ac guy can use these temperatures along with the pressures to determine if the system is serviced correctly.

Is a internally Clogged evaporator, symptomatically different than One that is externally, covered in dust?

This is my OCD obsession right now. I’m going to figure this out. Appreciate everyone’s help. I’m going to stop screwing around with this thing piecemeal and attack it as a system and just rip it all apart it’s gonna be terrible but worth it in the end

I'm watching this thread closely. Thanks for all that have contributed!

I am not real familiar with the Keith system, but the older R12 system had a hot gas by-pass valve controlled by a temp switch on the forward evaporator inlet line to keep the evaporator from freezing up. Just one more thing to look at ( if you have it ).

Probably for the best. If your going to turn it into a project, open it up, replace the drier and expansion valve with new, get the evap and condenser coil cleaned, pull a good vacuum on the system, preferably below 500 microns and recharge. If there is no weigh in data charge, charge it to 45-50 suction and you should be good. If at those pressure the suction line still won't get cool then add a little more. Then again if you start to see the suction line get cold at even 40psi suction then I would stop there, check the temp of the air coming out of the supply vents and see if it's good and not add anymore charge.

While there are some standards, depending on the design and engineering of the system the suction pressures on a good unit can be + or - 6 psi.

Also certain things can artificially raise or lower system pressures such as dirty evap or condenser coils and mild restrictions. That's why before really doing any troubleshooting you need to verify clean coils and good airflow over both coils.

The pressures your mechanic gave are really not that far off. But if your condenser coil is packed those pressure are going to be artificially raised to what you would think are good pressures but your actually low on charge and the pressures are just high because the condenser coil is restricted and raising the pressures in the system.

It's also possible there is a restriction and the pressures would then be lowered and some other mechanic kept cramming refrigerant into the system to get the pressures to where he though was acceptable but in reality the system is just over charged with a restriction.

These systems are pretty simple but there is a science to it. The pressures give good hints but being able to take temp readings of the suction and liquid line while in operation will give superheat and subcooling values of the refrigerant. This adds a whole other element to the troubleshooting process to make it much easier for the technician to understand what the refrigerant is doing in the system.

It would be very helpful to know if you have one of these installed in your system. It would be plumbed with a tee fitting somewhere downwind of the compressor (discharge line very hot) before it hits the condenser coil. If you have one installed that could change things.

Post some pictures of the process if you get the time please