so I am refilling a system.
it is custom, so no factory weights to use.
part of it is from a 5.9 durango, the rest is classic auto air, with custom cut lines. all of it is for r134a. it was a non-ac car.
First few times I had it filled, I think they just guessed. Gave me a weight of about 1.8 pounds.

It is about 100 degrees out side.
According to pressure charts, low side should be around 55 to 60 psi, and high side should be over 325 I think.
right now I get 15 for the low and 275 for the high.
I put in 48 oz.
harbor freight gauges, so for what they are worth.
It seems like it is still low then, and they just never put enough in the first couple of fills.

do I just keep adding till the low side comes up, as long as the high side doesn't go past?
just getting the 12oz cans right now.

did I go past where it was supposed to be? says most cars don't even use 24 oz.
I never saw the high side go up past 150 till I started adding the 3rd can.

blows pretty cold, but something is screwed up in my wiring and I can only get it to engage the compressor with the vents set to defrost, so I can't really measure, because I don't have and defrost vents lol.

what temperature do the outlets show, using a probe type thermometer ?
in a typical FSM, there are charts showing outlet temperature to outside temperature, as well as high and low side pressures compared to outside temperatures.
one thing you don't want to do is over charge the system.
how is it cooling/engaging the compressor clutch using defrost when you don't have defrost ?
i'm missing something here.
one of the components to be used in AC systems are a binary or trinary switch. one of these [or maybe both] are used to turn on the compressor clutch when the control switch is set to defrost.
using the AC in this mode removes the moisture on the glass quicker, in other words, a safety feature.

so the system has a defrost setting.
it goes to vents on the back of the box.
but I don't have any hoses that go to those vents.
So I can't measure the actual temps coming out.
mine has the binary switch. hi.low. I have a trinary, but took it off when I was having other issues.
I don't know why it won't run when I switch to the dash vents, but the compressor never kicks in.
I can see the compressor running when switched to defrost.

so I know it is doing something.
I am using the regular tables for r134a based on outside temps. Humidity is about 50 percent, which also alters the tables some.
but I saw at 95 degrees, around 107 psi static on the low side and 115 on the high side. Within the tolerance of the gauges.

I always heard people talk about not needing weight of refrigerant, that they could tell by the pressures.
but because I put so much in, everyone is saying it is over full, but it isn't acting like that.
While I don't want to waste the money, I am tempted to by a few more cans to see where it tops out at, since I haven't reached the pressures the tables say I should be at.

Your way overcharged. The 1.8 is pretty close to right in my opinion. No more than 2 pounds.