I bought a kit to test both the high and low side of the A/C system, in PSI (Not that red/yellow/blue/green "gauge" that comes with the cans).

I pretty much read 0 PSI on both the high and low side. I knew I had a leak.

I'm trying to put a little charge (1 can) into the system, and then add some dye so that I can find the leak. Problem is, it seems the system only took about 1/2 the can. I can shake it and feel refrigerant still in the can, but, it's not going into the truck. Do I have to just let it sit there running with the A/C on max and let it cycle a few times to suck all the refrigerant in?

Or, was I supposed to get a vaccuum in the system first before trying to add refrigerant?

 

Though I'm not a HVAC person, I've done the shade tree HVAC in the backyard. You need to pull a vacuum. Not only does this test for leaks, but it also "boils" everything bad out of the system before you put the good stuff in. Once you have a vacuum pulled, it should suck almost a whole can in by itself. One of the tricks I do to make sure it sucks it all in (especially on systems that the 1 can isn't enough to trip the low pressure switch) is to make a jumper for your low pressure switch so the compressor stays engaged all the time until you get enough in for it to run itself.

Of course all of the above is just fantasy, since you should technically have a licensed shop perform these types of things.

 

I see some dye it looks like inside the truck on a piece of foam. I'll stick the light up there again tonight when it gets dark. Can't see crap during the day. Looks like the dash may need to get ripped out!

 

You should pull a vacuum on the system, before charging it due to the oxygen that will be in a system without a vacuum pulled on it. Oxygen is an "oxidizer" and is detrimental to and AC system. Satburn is also correct about the jumping of the low pressure switch while charging and the rest of what he said.
In your case, if the dye is letting you know somehting with half a can in it, you're OK because you'll have to pull the systemm apart anyway to fix the leak. When you go to do the final charge, pull the vacuum first.

Chris

 

if you've got dye inside the cab on the passenger side, it's probably the evap core in the dash. Pretty common with these trucks. I think I bought mine at NAPA.

 

how much dose it cost to get a vacume pulled on the system

 

Usually you don't just get a vacuum pulled, you get the entire charge done by X shop. I don't know what they would charge, probably an hour's labor, as it takes 30+ minutes to evacuate the system properly.

Chris