Determining proper charge

[zz28zz]

As I've posted recently, I repaired my 2000 Corvette A/C after compressor failure. Everywhere I look online says sys takes 24 oz. That includes this site, 4-seasons site, an online factory service manual, and from local Chev dealership using vin number lookup. But for some reason the sticker under the hood says 1.75 lbs. I've always heard the sticker, on the pass fender in my case, is the holy grail, but fenders can be replaced and I bought car used.


Questions;
1. How is the proper charge determined originally?
2. Is it a percentage of total system volume?
2. Does the proper charge change when replacing condenser with an aftermarket version with possibly a different volume?

TIA

[Cusser]

3. Does the proper charge change when replacing condenser with an aftermarket version with possibly a different volume?

Yes, likely.

[JohnHere]

But for some reason the sticker under the hood says 1.75 lbs. I've always heard the sticker, on the pass fender in my case, is the holy grail, but fenders can be replaced and I bought car used.

If there's any doubt, I think I would charge the system to 24 ounces and then see how it performs. If the pressures seem a bit low and/or the center vent temperatures seem elevated, then I would add 4 ounces gradually while watching the pressures.

Questions;
1. How is the proper charge determined originally?
2. Is it a percentage of total system volume?

Not having been a system designer, I can't say for sure. But I presume that Question #2 is at least a factor in the calculation, as is the oil amount.