Less is more. 134a is more sensitive to overcharging than r-12, so you really need to be careful and very slow. Use real gauges, watch high and low sides, and use a sensitive digital thermometer to keep watching temps drop. As soon as they gonzo one degree, stop.

Use a giant pusher fan to keep the condenser working at a steady rate.

__________________
Current Diesels:
1981 240D (73K)
1982 300CD (169k)
1985 190D (169k)
1991 350SD (116k)
1991 350SD (206k)
1991 300D (228k)
2008 ML320 CDI (199k)
1996 Dodge Ram CTD (442k)
1996 Dodge Ram CTD (267k)

Past Diesels:
1983 300D (228K), 1985 300D (233K), 1993 300D 2.5T (338k), 1993 300SD (291k)

Less is more? Should I let out the 134 that's in there?

Seriously, I want to get it as cold as possible. I have manifold gauges, I have a digital thermocouple meter for fast response. I just want to do the rest right w/o blowing it up.

I hear the pros on here charge by weight then final by vent temp to get it as cold as possible. So there must be some techniques they use w/o over doing it.

__________________
85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked