On my W126 300SEL The air is not cold.

The compressor kicks on but I am not getting much cooling if any, I know theses systems are somewhat complex but it seems to me like the appropriate vents are opening and closing based upon the different modes.

I have 2 cans of R12 but have read that "topping it off" is not advisable because you are not filling to the proper level and I don't have enough coolant to replace all of it. I also cannot seem to find a shop that will mess with R12 to even evacuate it properly.

I live in NC and want to daily drive this car but the summer here is no joke.

I spoke to a shop that suggested I just top off the R12 by adding it to the low side and watch the sight glass carefully to ensure the bubbles dissipate and call it good.

I am floating in the dark here as my expertise here is very limited.

Chris