A 1990 model year vehicle would have come from the factory with a system which uses R-12 refrigerant. If you're not the original owner of the vehicle, I would recommend having a refrigerant purity test done to determine whether it is still an R-12 system, or if it has been converted to R-134a.
How much freon does it take for a 2000 Chevy full size truck
A135
R134a
Should take aprox 30 ounces of freon.
R134A
It depends on the year and witch type of freon you have but on a 2003 model it will take 1.6 pounds of R134a freon................
R-134a
R-134a
1lb 6oz
The average amount of pounds a Chevy Caprice would take is 3 to 4 pounds. Freon is difficult to obtain and you have to know what you are doing to charge a car.
24x3
It was built for R12, can be retrofitted to R134a