1993 AC specs for capacity?

[WarWagon]

Ok what changed from 1993 to 1994+ in pickups? The different capacities do not make sense.
1993 appears to have both factory R12 and R134A systems.

The 1993 R12 specs are 40 oz R12 aka 2.5 LBS and 8 oz oil. My 1993 had a sticker saying this and the book agrees.
The 1993 R134A specs are the same 40 oz. (I understand the condenser is bigger. Also the compressor ports are different heights with R12 being flat and the R134a stepped. Requires different thickness sealing washers to run a 134a design in the R12 system. They don't make the R12 design anymore rather they now come with the different height sealing washers for the ports...)
1994 and later years are 2 LBS aka 32 oz R134A by the book.

R134a conversions is 10% less than the R12 spec. Thus 36 oz of R134a in the R12 system.

Assuming you keep the R12 condenser you would be at 10% of the R12 during the retrofit. Now what happens when you put in the larger R134a condenser like do you go with 40 oz? Why are 1994 and later years less Freon? Maybe book I have wrong for 1994+ years? Or did something shrink?

 

[THEFERMANATOR]

Condensers didn't change until 94, and I would venture to say the 40 once 93 spec for 134 is a mis print. You want to use 75-80% of the R-12 spec when you use R134 to retrofit one. it is just simple physics that R-134A is rougjly 75% of the weight of R-12 per volume amount. Also in 94 GM moved the orifice tube from the evap to the condenser for single air units which offset the condenser size change for charge amount. The #1 thing to keep in mind when charging a system is to NEVER EVER allow liquid to make it to the compressor as this will kill one INSTANTLY! this is why i like to charge by line temp VS ambient and use the pressures as a referenece. When you charge by temp you can also tell if your oil quantity is correct or not.