If it wasn’t for the fact you want to install the firewall thing and have to open the lines anyway I would say just tie the compressor up somewhere and not even bother cracking the lines then leave the rest of the accessories on the engine. I typically always pull engines with accessories still bolted to them, especially light engines like small blocks or a V6, but I tie up the A/C compressor under the hood and never crack a line. Being you are going to open the lines anyway, just let her rip and let the refrigerant go and don’t tell anybody, like in a public forum
It is irresponsible for a place of business to use such a practice but think about all of the auto accidents that happen every day where condensers are smashed open while releasing refrigerant into the atmosphere. If loosing refrigerant into the atmosphere was such a huge catastrophe you would think the feds would require auto manufacturers to engineering a method of making a leak and crash proof A/C systems. Maybe all of the loose R134A floating around the atmosphere is why here are no more unicorns. I dunno…. Of course, in the Republic of Kalifornia you can’t even fart without a catalytic converter in your Fruit of a Looms. Better not let your neighbor hear the A/C line hissing once you crack it open
Never cracked a line on this Suburban. Subs with rear A/C hold A LOT of refrigerant and I didn’t want to waste any
PS.....I would not recommend pulling the trans and engine together. That is a great way to loose a lot of ATF on your driveway causing more catastrophe to the environment and pulling the radiator support is a huge waste of time but that is just me. Pull the engine over the rad support then it will take you about 10 minutes to drop the trans down by itself. That is my method.....Cleaner that way.