Hi All,
I searched, but couldn't find a specific answer to my question. I have changed the low pressure side switch and the AC works better now. I still am not sure about the quantity of refrigerant. I currently have 1.8 lbs as specified on the little sticker. But, should I purge the system and replace with 1.6 lbs.? I have seen this recomended, but not sure if it applies to the '01.
Thanks,
Jim
2001 C3500 Duramax

if not sure how much you got you should totally evacuate the system. Then pull a good vacumm with a thermistor gauge that indicates microns. You may want to consult a dealer or a/c shop for micron range to pull it down to, remember to pull it down to those numbers because that is how you remove the moisture from the system this will give you a nice long life out of the system with few problems.Reservice with correct amount given and you should be good to go. Because remember if your just adding freon you dont know what the system has in it to much freon will drag the compressor down and will not cool as well.

You need to ask one of the tech's in the ask the tech category. I don't remember if the TSB replaced anything else or, they just dropped the charge down.

I assume you know enough about HVAC to have already done what Mattgofast said to do.

There is a coorolation between critical charge and suction pressure, but I don't remember what that is for an R134A unit.

Fortunately, for most backyard and hack professionals, moisture in an A/C unit with an open drive is not nearly as big of deal as the hermetic units.