Evaporator removal 95 se

[Paintjar]

Been reading the posts I could find on this job for some help. Old links to photos no longer work. I discovered some say you need to get it from the inside as well as the outside. Most agree, heater core inside job and evaporator core outside job. I am going the outside first. One post I have to agree with is, there is ONE screw on the inside that holds the cover. That is where I am now. Going to tear into the inside and hunt down this screw tomorrow. I am going to try this without pulling the dash out. So I guess you might say its an in and out job. I need help understanding the accumulator. Should I dump out all the liquid that is in there?
The other thing is the plastic housing over the fan and evaporator. This thing just feel apart. Everyplace I touched it fell apart. What is a good substitute for this to hold the insulation in place after I assemble the cover. Any ideas? Thanks for any input.

[Paintjar]

After checking the service manual I found that the a/c system requires about 8 oz oil. If replacing the major components it says add so many oz to the system. That answers my question about dumping out the liquid (about 3 oz) in the accumulator. I was wondering if I can put oil directly back in there or if I should add to the system through the valve where I add 134. The evaporator is a little different (another 3 oz) and probably not a good idea to try and pour oil into it directly. The compressor requires you to add oil directly to it before you install it ( comes with the new oil). Has anyone added oil to the system after replacing the evaporator or accumulator?
I am finding that there are different ratings of oil. PAG 100 ,46, 150 or 135. I can not find in the service manual which one is required. Mostly see 100 for sale. Which PAG should I use?

[Paintjar]

After further checking I have found that most GM compressors require 150. I best check with A/C expert on this or damage could result with wrong viscosity.
This info was from https://www.aa1car.com/library/pagoil.htm

[Paintjar]

Success! Got the evaporator out without going inside. The ONE screw they put at the bottom was an easy work around. Its a squre plastic insert with wings to hold it then screw from inside. Well I just clipped the wings off and wallah cover came off. I see no need for this screw. I can put a new square in it and screw it later when I am in the dash for another reason. What a mess in there as everyone who takes apart will tell you. They need a simple service door to periodically clean it out. Fan will blow more air for sure. Parts on order. Still wondering about the oil weight. Dumping out the accumulator is good. Just measure the amount you take out and add according to service manual. The new compressor came with 150 when I installed it last year, so I am going with that. The Freon carries the oil through the system ,so adding is done through the port, except when you install a new compressor. That is poured directly into it. Learning a lot with the manuals. Keeping the old girl in tip top condition feels good.