A/C Charge by Myself
Is it perhaps a difference between automotive and other types of HVAC and refrigeration?
No. No difference. The ONLY reason they teach low side only is because some of these folks don't have that much experience, and no one wants to "chance" a liquid slug into a compressor.
The ONLY THING you are doing, here, on the high side IS WITH THE SYSTEM STOPPED. You are doing what amounts to the "same thing" that the condenser is doing, IE sending "high pressure" liquid from the high side to the low side.
As long as you don't "dump" any liquid into the low side, there is zero chance of ever hurting a compressor.
I'm not saying you HAVE to do this. I'm saying that claiming it is damaging is wrong. When you get into larger systems, and it matters not whether they are high, med, or low temp systems, you get something that holds 5 lb or more of gas, you will be there all week long trying to charge it with gas on the low side.
This in my mind, is just one more example of "skeered liability" gone amuck. One of my favorites is I used to have a plastic case of KD tool cold chisels. The federal warning said "do not strike with hard metallic object." I guess a ball pein hammer is out of the question!!
