A/C Pag Oil Capacity?

LongrangeLauber · September 29

Doing a full overhaul on the A/C in the truck (2014 Silverado 1500, 4wd, 5.3L) and am finding conflicting info regarding the PAG oil capacity for the total system. One website claims 3.4oz, the other claims 7.1oz.

Everything is brand new besides the evaporator (compressor, lines, condenser, TXV). I also did a flush on the evaporator since I have it opened up. Everything is dry (minus the 3oz GM put into the replacement compressor.) Just need some solid info on which is correct, or is the 3oz already added to the replacement compressor enough for the entire system?

Also, if I do need to add more to the system, just dump the PAG all into the compressor, or distribute it amongst the parts (1oz here, 1oz there, etc)? Thanks all!

CamGTP · September 29

If you sucked the whole system dry with a AC machine and had no oil in the compressor it's about that 7oz. Even an AC machine will never get it all out, some will always be trapped in some of the hard lines or inside the evap core. If the new compressor has oil in it already just take that into account.

You can't add the oil to the lines or anything else right now anyway because you must vacuum down the system prior to putting in new freon, you can't just add the freon with air in the system. If all the oil to the lines, it'll just get sucked out when you vacuum it down, Mostly all of the oil will stay in the compressor when using just a vacuum pump.

So install all the parts, vacuum it down, then add in a little extra oil when you add in the R134a. Honestly close enough is good enough, I've done so many parts changes with and without AC machines as I have my own set of gauges and a vacuum pump. I really don't suck that much oil out with a vacuum pump, so I just add a little bit back in when I add in the freon, never had a problem doing it that way.